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HL Paper 2

The function  f is defined by f ( x ) = 2 ln x + 1 x 3 , 0 <  x < 3.

Draw a set of axes showing  x and  y  values between −3 and 3. On these axes

Hence, or otherwise, find the coordinates of the point of inflexion on the graph of  y = f ( x ) .

[4]
b.

sketch the graph of y = f ( x ) , showing clearly any axis intercepts and giving the equations of any asymptotes.

[4]
c.i.

sketch the graph of y = f 1 ( x ) , showing clearly any axis intercepts and giving the equations of any asymptotes.

[4]
c.ii.

Hence, or otherwise, solve the inequality f ( x ) > f 1 ( x ) .

[3]
d.



Consider f ( x ) = 1 + ln ( x 2 1 )

The function f is defined by f ( x ) = 1 + ln ( x 2 1 ) ,   x D

The function g is defined by g ( x ) = 1 + ln ( x 2 1 ) ,   x ] 1 ,   [ .

Find the largest possible domain D for f to be a function.

[2]
a.

Sketch the graph of y = f ( x ) showing clearly the equations of asymptotes and the coordinates of any intercepts with the axes.

[3]
b.

Explain why f is an even function.

[1]
c.

Explain why the inverse function f 1 does not exist.

[1]
d.

Find the inverse function g 1 and state its domain.

[4]
e.

Find g ( x ) .

[3]
f.

Hence, show that there are no solutions to  g ( x ) = 0 ;

[2]
g.i.

Hence, show that there are no solutions to  ( g 1 ) ( x ) = 0 .

[2]
g.ii.



A scientist conducted a nine-week experiment on two plants, A and B, of the same species. He wanted to determine the effect of using a new plant fertilizer. Plant A was given fertilizer regularly, while Plant B was not.

The scientist found that the height of Plant A, hA cm, at time t weeks can be modelled by the function hA(t)=sin(2t+6)+9t+27, where 0t9.

The scientist found that the height of Plant B, hB cm, at time t weeks can be modelled by the function hB(t)=8t+32, where 0t9.

Use the scientist’s models to find the initial height of

Plant B.

[1]
a.i.

Plant A correct to three significant figures.

[2]
a.ii.

Find the values of t when hAt=hBt.

[3]
b.

For t>6, prove that Plant A was always taller than Plant B.

[3]
c.

For 0t9, find the total amount of time when the rate of growth of Plant B was greater than the rate of growth of Plant A.

[6]
d.



The voltage v in a circuit is given by the equation

v ( t ) = 3 sin ( 100 π t ) t 0  where t is measured in seconds.

The current i in this circuit is given by the equation

i ( t ) = 2 sin ( 100 π ( t + 0.003 ) ) .

The power p in this circuit is given by p ( t ) = v ( t ) × i ( t ) .

The average power  p a v in this circuit from t = 0 to t = T is given by the equation

p a v ( T ) = 1 T 0 T p ( t ) d t , where  T > 0 .

Write down the maximum and minimum value of v .

[2]
a.

Write down two transformations that will transform the graph of y = v ( t ) onto the graph of y = i ( t ) .

[2]
b.

Sketch the graph of y = p ( t ) for 0 ≤ t ≤ 0.02 , showing clearly the coordinates of the first maximum and the first minimum.

[3]
c.

Find the total time in the interval 0 ≤ t ≤ 0.02 for which  p ( t )  ≥ 3.

 

[3]
d.

Find p a v (0.007).

 

[2]
e.

With reference to your graph of  y = p ( t )  explain why  p a v ( T ) > 0 for all T > 0.

 

[2]
f.

Given that p ( t ) can be written as  p ( t ) = a sin ( b ( t c ) ) + d  where a b c d > 0, use your graph to find the values of a b c  and d .

 

[6]
g.



Consider the function fx=x2-x-122x-15, x, x152.

Find the coordinates where the graph of f crosses the

x-axis.

[2]
a.i.

y-axis.

[1]
a.ii.

Write down the equation of the vertical asymptote of the graph of f.

[1]
b.

The oblique asymptote of the graph of f can be written as y=ax+b where a, b.

Find the value of a and the value of b.

[4]
c.

Sketch the graph of f for -30x30, clearly indicating the points of intersection with each axis and any asymptotes.

[3]
d.

Express 1fx in partial fractions.

[3]
e.i.

Hence find the exact value of 031fxdx, expressing your answer as a single logarithm.

[4]
e.ii.



The function f is defined by  f ( x ) = sec x + 2 , 0 x < π 2 .

Write down the range of f .

[1]
a.

Find f-1(x), stating its domain.

[4]
b.



The population, P, of a particular species of marsupial on a small remote island can be modelled by the logistic differential equation

dPdt=kP1-PN

where t is the time measured in years and k, N are positive constants.

The constant N represents the maximum population of this species of marsupial that the island can sustain indefinitely.

Let P0 be the initial population of marsupials.

In the context of the population model, interpret the meaning of dPdt.

[1]
a.

Show that d2Pdt2=k2P1-PN1-2PN.

[4]
b.

Hence show that the population of marsupials will increase at its maximum rate when P=N2. Justify your answer.

[5]
c.

Hence determine the maximum value of dPdt in terms of k and N.

[2]
d.

By solving the logistic differential equation, show that its solution can be expressed in the form

kt=lnPP0N-P0N-P.

[7]
e.

After 10 years, the population of marsupials is 3P0. It is known that N=4P0.

Find the value of k for this population model.

[2]
f.



Consider the function f ( x ) = 2 sin 2 x + 7 sin 2 x + tan x 9 ,   0 x < π 2 .

Let u = tan x .

Determine an expression for f ( x ) in terms of x .

[2]
a.i.

Sketch a graph of y = f ( x ) for 0 x < π 2 .

[4]
a.ii.

Find the x -coordinate(s) of the point(s) of inflexion of the graph of y = f ( x ) , labelling these clearly on the graph of y = f ( x ) .

[2]
a.iii.

Express sin x in terms of u.

[2]
b.i.

Express sin 2 x in terms of u .

[3]
b.ii.

Hence show that f ( x ) = 0 can be expressed as u 3 7 u 2 + 15 u 9 = 0 .

[2]
b.iii.

Solve the equation f ( x ) = 0 , giving your answers in the form arctan k where k Z .

[3]
c.



Consider the polynomial P ( z ) z 4 6 z 3 2 z 2 + 58 z 51 , z C .

Sketch the graph of y = x 4 6 x 3 2 x 2 + 58 x 51 , stating clearly the coordinates of any maximum and minimum points and intersections with axes.

[6]
b.

Hence, or otherwise, state the condition on k R such that all roots of the equation P ( z ) = k are real.

[2]
c.



A curve C is given by the implicit equation  x + y cos ( x y ) = 0 .

The curve  x y = π 2  intersects C at P and Q.

Show that  d y d x = ( 1 + y sin ( x y ) 1 + x sin ( x y ) ) .

[5]
a.

Find the coordinates of P and Q.

[4]
b.i.

Given that the gradients of the tangents to C at P and Q are m1 and m2 respectively, show that m1 × m2 = 1.

[3]
b.ii.

Find the coordinates of the three points on C, nearest the origin, where the tangent is parallel to the line  y = x .

[7]
c.



A large tank initially contains pure water. Water containing salt begins to flow into the tank The solution is kept uniform by stirring and leaves the tank through an outlet at its base. Let x grams represent the amount of salt in the tank and let t minutes represent the time since the salt water began flowing into the tank.

The rate of change of the amount of salt in the tank, d x d t , is described by the differential equation d x d t = 10 e t 4 x t + 1 .

Show that t + 1 is an integrating factor for this differential equation.

[2]
a.

Hence, by solving this differential equation, show that x ( t ) = 200 40 e t 4 ( t + 5 ) t + 1 .

[8]
b.

Sketch the graph of x versus t for 0 ≤ t ≤ 60 and hence find the maximum amount of salt in the tank and the value of t at which this occurs.

[5]
c.

Find the value of t at which the amount of salt in the tank is decreasing most rapidly.

[2]
d.

The rate of change of the amount of salt leaving the tank is equal to x t + 1 .

Find the amount of salt that left the tank during the first 60 minutes.

[4]
e.



Consider the differential equation x2dydx=y2-2x2 for x>0 and y>2x. It is given that y=3 when x=1.

Use Euler’s method, with a step length of 0.1, to find an approximate value of y when x=1.5.

[4]
a.

Use the substitution y=vx to show that xdvdx=v2-v-2.

[3]
b.

By solving the differential equation, show that y=8x+x44-x3.

[10]
c.i.

Find the actual value of y when x=1.5.

[1]
c.ii.

Using the graph of y=8x+x44-x3, suggest a reason why the approximation given by Euler’s method in part (a) is not a good estimate to the actual value of y at x=1.5.

[1]
c.iii.



Consider the function fx=x2-1, where 1x2.

The curve y=f(x) is rotated 2π about the y-axis to form a solid of revolution that is used to model a water container.

At t=0, the container is empty. Water is then added to the container at a constant rate of 0.4m3s-1.

Sketch the curve y=fx, clearly indicating the coordinates of the endpoints.

[2]
a.

Show that the inverse function of f is given by f-1x=x2+1.

[3]
b.i.

State the domain and range of f-1.

[2]
b.ii.

Show that the volume, Vm3, of water in the container when it is filled to a height of h metres is given by V=π13h3+h.

[3]
c.i.

Hence, determine the maximum volume of the container.

[2]
c.ii.

Find the time it takes to fill the container to its maximum volume.

[2]
d.

Find the rate of change of the height of the water when the container is filled to half its maximum volume.

[6]
e.



The following diagram shows the curve x236+y-4216=1, where hy4.

The curve from point Q to point B is rotated 360° about the y-axis to form the interior surface of a bowl. The rectangle OPQR, of height hcm, is rotated 360° about the y-axis to form a solid base.

The bowl is assumed to have negligible thickness.

Given that the interior volume of the bowl is to be 285cm3, determine the height of the base.




The function f is defined by  f ( x ) = sec x + 2 , 0 x < π 2 .

Use integration by parts to find ( ln x ) 2 d x .




Two airplanes, A and B, have position vectors with respect to an origin O given respectively by

rA=19-11+t-624

rB=1012+t42-2

where t represents the time in minutes and 0t2.5.

Entries in each column vector give the displacement east of O, the displacement north of O and the distance above sea level, all measured in kilometres.

The two airplanes’ lines of flight cross at point P.

Find the three-figure bearing on which airplane B is travelling.

[2]
a.

Show that airplane A travels at a greater speed than airplane B.

[2]
b.

Find the acute angle between the two airplanes’ lines of flight. Give your answer in degrees.

[4]
c.

Find the coordinates of P.

[5]
d.i.

Determine the length of time between the first airplane arriving at P and the second airplane arriving at P.

[2]
d.ii.

Let D(t) represent the distance between airplane A and airplane B for 0t2.5.

Find the minimum value of D(t).

[5]
e.



Xavier, the parachutist, jumps out of a plane at a height of h metres above the ground. After free falling for 10 seconds his parachute opens. His velocity, v m s 1 , t seconds after jumping from the plane, can be modelled by the function

v ( t ) = { 9.8 t , 0 t 10 98 1 + ( t 10 ) 2 , t > 10

His velocity when he reaches the ground is 2.8  m s 1 .

Find his velocity when t = 15 .

[2]
a.

Calculate the vertical distance Xavier travelled in the first 10 seconds.

[2]
b.

Determine the value of h .

[5]
c.



Consider limx0arctancosx-kx2, where k.

Show that a finite limit only exists for k=π4.

[2]
a.

Using l’Hôpital’s rule, show algebraically that the value of the limit is -14.

[6]
b.



A particle P moves in a straight line such that after time t seconds, its velocity, v in m s-1, is given by v=e3tsin6t, where 0<t<π2.

At time t, P has displacement s(t); at time t=0, s(0)=0.

At successive times when the acceleration of P is 0m s2 , the velocities of P form a geometric sequence. The acceleration of P is zero at times t1, t2, t3 where t1<t2<t3 and the respective velocities are v1, v2, v3.

Find the times when P comes to instantaneous rest.

[2]
a.

Find an expression for s in terms of t.

[7]
b.

Find the maximum displacement of P, in metres, from its initial position.

[2]
c.

Find the total distance travelled by P in the first 1.5 seconds of its motion.

[2]
d.

Show that, at these times, tan6t=2.

[2]
e.i.

Hence show that v2v1=v3v2=-e-π2.

[5]
e.ii.



The following diagram shows part of the graph of 2 x 2 = si n 3 y for 0 y π .

The shaded region R is the area bounded by the curve, the y -axis and the lines y = 0 and y = π .

Using implicit differentiation, find an expression for d y d x .

[4]
a.i.

Find the equation of the tangent to the curve at the point  ( 1 4 5 π 6 ) .

[4]
a.ii.

Find the area of R .

[3]
b.

The region R is now rotated about the y -axis, through 2 π radians, to form a solid.

By writing  si n 3 y as  ( 1 co s 2 y ) sin y , show that the volume of the solid formed is 2 π 3 .

[6]
c.



The following diagram shows part of the graph of y=p+qsin(rx) . The graph has a local maximum point at -9π4, 5 and a local minimum point at -3π4, -1.

Determine the values of p, q and r.

[4]
a.

Hence find the area of the shaded region.

[4]
b.



A function  f satisfies the conditions  f ( 0 ) = 4 f ( 1 ) = 0 and its second derivative is f ( x ) = 15 x + 1 ( x + 1 ) 2 , x ≥ 0.

Find f ( x ) .




A point P moves in a straight line with velocity v  ms−1 given by v ( t ) = e t 8 t 2 e 2 t at time t seconds, where t ≥ 0.

Determine the first time t1 at which P has zero velocity.

[2]
a.

Find an expression for the acceleration of P at time t.

[2]
b.i.

Find the value of the acceleration of P at time t1.

[1]
b.ii.



Let l be the tangent to the curve y = x e 2 x at the point (1, e 2 ).

Find the coordinates of the point where l meets the x -axis.




A body moves in a straight line such that its velocity,  v m s 1 , after t  seconds is given by v = 2 sin ( t 10 + π 5 ) csc ( t 30 + π 4 ) for  0 t 60 .

The following diagram shows the graph of v against t . Point A is a local maximum and point B is a local minimum.

The body first comes to rest at time t = t 1 . Find

Determine the coordinates of point A and the coordinates of point B .

[4]
a.i.

Hence, write down the maximum speed of the body.

[1]
a.ii.

the value of  t 1 .

[2]
b.i.

the distance travelled between  t = 0 and  t = t 1 .

[2]
b.ii.

the acceleration when t = t 1 .

[2]
b.iii.

Find the distance travelled in the first 30 seconds.

[3]
c.



A water trough which is 10 metres long has a uniform cross-section in the shape of a semicircle with radius 0.5 metres. It is partly filled with water as shown in the following diagram of the cross-section. The centre of the circle is O and the angle KOL is θ radians.

M17/5/MATHL/HP2/ENG/TZ1/08

The volume of water is increasing at a constant rate of 0.0008   m 3 s 1 .

Find an expression for the volume of water V   ( m 3 ) in the trough in terms of θ .

[3]
a.

Calculate d θ d t when θ = π 3 .

[4]
b.



The function f is defined by fx=3x+24x2-1, for xxpxq.

The graph of y=f(x) has exactly one point of inflexion.

The function g is defined by gx=4x2-13x+2, for x, x-23.

Find the value of p and the value of q.

[2]
a.

Find an expression for f'x.

[3]
b.

Find the x-coordinate of the point of inflexion.

[2]
c.

Sketch the graph of y=f(x) for -3x3, showing the values of any axes intercepts, the coordinates of any local maxima and local minima, and giving the equations of any asymptotes.

[5]
d.

Find the equations of all the asymptotes on the graph of y=g(x).

[4]
e.

By considering the graph of y=g(x)-f(x), or otherwise, solve f(x)<g(x) for x.

[4]
f.



The region A is enclosed by the graph of y = 2 arcsin ( x 1 ) π 4 , the y -axis and the line y = π 4 .

Write down a definite integral to represent the area of A .

[4]
a.

Calculate the area of A .

[2]
b.



The following graph shows the two parts of the curve defined by the equation x 2 y = 5 y 4 , and the normal to the curve at the point P(2 , 1).

 

Show that there are exactly two points on the curve where the gradient is zero.

[7]
a.

Find the equation of the normal to the curve at the point P.

[5]
b.

The normal at P cuts the curve again at the point Q. Find the x -coordinate of Q.

[3]
c.

The shaded region is rotated by 2 π about the y -axis. Find the volume of the solid formed.

[7]
d.



The function f has a derivative given by f'x=1xk-x, x, xo, xk where k is a positive constant.

Consider P, the population of a colony of ants, which has an initial value of 1200.

The rate of change of the population can be modelled by the differential equation dPdt=Pk-P5k, where t is the time measured in days, t0, and k is the upper bound for the population.

At t=10 the population of the colony has doubled in size from its initial value.

The expression for f(x) can be written in the form ax+bk-x, where a, b. Find a and b in terms of k.

[3]
a.

Hence, find an expression for f(x).

[3]
b.

By solving the differential equation, show that P=1200kk-1200e-t5+1200.

[8]
c.

Find the value of k, giving your answer correct to four significant figures.

[3]
d.

Find the value of t when the rate of change of the population is at its maximum.

[3]
e.



Write down the first three terms of the binomial expansion of (1+t)-1 in ascending powers of t.

[1]
a.

By using the Maclaurin series for cosx and the result from part (a), show that the Maclaurin series for secx up to and including the term in x4 is 1+x22+5x424.

[4]
b.

By using the Maclaurin series for arctanx and the result from part (b), find limx0x arctan2xsecx-1.

[3]
c.



A function f is defined by fx=kex21+ex, where x, x0 and k+.

The region enclosed by the graph of y=f(x), the x-axis, the y-axis and the line x=ln16 is rotated 360° about the x-axis to form a solid of revolution.

Pedro wants to make a small bowl with a volume of 300cm3 based on the result from part (a). Pedro’s design is shown in the following diagrams.

The vertical height of the bowl, BO, is measured along the x-axis. The radius of the bowl’s top is OA and the radius of the bowl’s base is BC. All lengths are measured in cm.

For design purposes, Pedro investigates how the cross-sectional radius of the bowl changes.

Show that the volume of the solid formed is 15k2π34 cubic units.

[6]
a.

Find the value of k that satisfies the requirements of Pedro’s design.

[2]
b.

Find OA.

[2]
c.i.

Find BC.

[2]
c.ii.

By sketching the graph of a suitable derivative of f, find where the cross-sectional radius of the bowl is decreasing most rapidly.

[4]
d.i.

State the cross-sectional radius of the bowl at this point.

[2]
d.ii.



The function f is defined by  f ( x ) = ( x 1 ) 2 x  ≥ 1 and the function g is defined by g ( x ) = x 2 + 1 x  ≥ 0.

The region R is bounded by the curves  y = f ( x ) y = g ( x )  and the lines  y = 0 x = 0 and  y = 9  as shown on the following diagram.

The shape of a clay vase can be modelled by rotating the region R through 360˚ about the y -axis.

Find the volume of clay used to make the vase.




Consider the function f ( x ) = x sin x ,   0 < x < π .

Consider the region bounded by the curve y = f ( x ) , the x -axis and the lines x = π 6 ,   x = π 3 .

Show that the x -coordinate of the minimum point on the curve y = f ( x ) satisfies the equation tan x = 2 x .

[5]
a.i.

Determine the values of x for which f ( x ) is a decreasing function.

[2]
a.ii.

Sketch the graph of y = f ( x ) showing clearly the minimum point and any asymptotic behaviour.

[3]
b.

Find the coordinates of the point on the graph of f where the normal to the graph is parallel to the line y = x .

[4]
c.

This region is now rotated through 2 π radians about the x -axis. Find the volume of revolution.

[3]
d.



Consider the differential equation

dydx=fyx, x>0

The curve y=fx for x>0 has a gradient function given by

dydx=y2+3xy+2x2x2.

The curve passes through the point 1,-1.

Use the substitution y=vx to show that dvfv-v=lnx+C where C is an arbitrary constant.

[3]
a.

By using the result from part (a) or otherwise, solve the differential equation and hence show that the curve has equation y=xtanlnx-1.

[9]
b.

The curve has a point of inflexion at x1,y1 where e-π2<x1<eπ2. Determine the coordinates of this point of inflexion.

[6]
c.

Use the differential equation dydx=y2+3xy+2x2x2 to show that the points of zero gradient on the curve lie on two straight lines of the form y=mx where the values of m are to be determined.

[4]
d.



Consider the curve defined by the equation 4 x 2 + y 2 = 7 .

Find the volume of the solid formed when the region bounded by the curve, the x -axis for x 0 and the y -axis for y 0 is rotated through 2 π about the x -axis.




A function f is defined by fx=arcsinx2-1x2+1, x.

A function g is defined by gx=arcsinx2-1x2+1, x, x0.

Show that f is an even function.

[1]
a.

By considering limits, show that the graph of y=f(x) has a horizontal asymptote and state its equation.

[2]
b.

Show that f'x=2xx2x2+1 for x, x0.

[6]
c.i.

By using the expression for f'x and the result x2=x, show that f is decreasing for x<0.

 

[3]
c.ii.

Find an expression for g-1(x), justifying your answer.

[5]
d.

State the domain of g-1.

[1]
e.

Sketch the graph of y=g-1(x), clearly indicating any asymptotes with their equations and stating the values of any axes intercepts.

[3]
f.



The curve C is defined by equation x y ln y = 1 ,   y > 0 .

Find d y d x in terms of x and y .

[4]
a.

Determine the equation of the tangent to C at the point ( 2 e ,  e )

[3]
b.



Differentiate from first principles the function f ( x ) = 3 x 3 x .




By using the substitution x 2 = 2 sec θ , show that d x x x 4 4 = 1 4 arccos ( 2 x 2 ) + c .




A continuous random variable X has the probability density function f given by

fx=xx2+k3        0x4      0                 otherwise

where k+.

Show that 16+k-k=k16+k.

[5]
a.

Find the value of k.

[2]
b.



The curve C has equation e2y=x3+y.

Show that dydx=3x22e2y-1.

[3]
a.

The tangent to C at the point Ρ is parallel to the y-axis.

Find the x-coordinate of Ρ.

[4]
b.



Given that  2 x 3 3 x + 1 can be expressed in the form  A x ( x 2 + 1 ) + B x + C , find the values of the constants  A B and  C .

[2]
a.

Hence find 2 x 3 3 x + 1 x 2 + 1 d x .

[5]
b.



A particle moves along a horizontal line such that at time t seconds, t ≥ 0, its acceleration a is given by a = 2 t − 1. When t = 6 , its displacement s from a fixed origin O is 18.25 m. When t = 15, its displacement from O is 922.75 m. Find an expression for s in terms of t .




Consider the curve C given by y=x-xyln(xy) where x>0, y>0.

Show that dydx+xdydx+y1+lnxy=1.

[3]
a.

Hence find the equation of the tangent to C at the point where x=1.

[5]
b.



Consider the differential equation dydx=y-xy+x, where x, y>0.

It is given that y=2 when x=1.

Solve the differential equation, giving your answer in the form fx,y=0.

[9]
a.

The graph of y against x has a local maximum between x=2 and x=3. Determine the coordinates of this local maximum.

[4]
b.

Show that there are no points of inflexion on the graph of y against x.

[4]
c.



Assuming the Maclaurin series for cosx and ln(1+x), show that the Maclaurin series for cos(ln(1+x)) is

1-12x2+12x3-512x4+

[4]
a.

By differentiating the series in part (a), show that the Maclaurin series for sin(ln(1+x)) is x-12x2+16x3+ .

[4]
b.

Hence determine the Maclaurin series for tan(ln(1+x)) as far as the term in x3.

[5]
c.



Two boats A and B travel due north.

Initially, boat B is positioned 50 metres due east of boat A.

The distances travelled by boat A and boat B, after t seconds, are x metres and y metres respectively. The angle θ is the radian measure of the bearing of boat B from boat A. This information is shown on the following diagram.

Show that y=x+50cotθ .

[1]
a.

At time T, the following conditions are true.

Boat B has travelled 10 metres further than boat A.
Boat B is travelling at double the speed of boat A.
The rate of change of the angle θ is -0.1 radians per second.

Find the speed of boat A at time T.

[6]
b.



A small bead is free to move along a smooth wire in the shape of the curve y=103-2e-0.5xx0.

Find an expression for dydx.

[3]
a.

At the point on the curve where x=4, it is given that dydt=-0.1m s-1

Find the value of dxdt at this exact same instant.

[3]
b.



An earth satellite moves in a path that can be described by the curve 72.5 x 2 + 71.5 y 2 = 1 where x = x ( t ) and y = y ( t ) are in thousands of kilometres and t is time in seconds.

Given that d x d t = 7.75 × 10 5 when x = 3.2 × 10 3 , find the possible values of d y d t .

Give your answers in standard form.