Question Bank

Official NZQA past exam questions • AS91578 Differentiation

With video explanations by infinityplusone

15 questions
Achievement
Differentiate y=x+tan(2x)y = \sqrt{x} + \tan(2x).
Achievement
Find the gradient of the tangent to the curve y=e2xx+2y = \dfrac{e^{2x}}{x + 2} at the point where x=0x = 0.

*You must use calculus and show any derivatives that you need to find when solving this problem.*
The normal to the parabola y=0.5(x3)2+2y = 0.5(x - 3)^2 + 2 at the point (1,4)(1,4) intersects the parabola again
at the point P.
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Find the xx-coordinate of point P.

*You must use calculus and show any derivatives that you need to find when solving this
problem.*
A curve is defined parametrically by the equations x=t+1x = \sqrt{t + 1} and y=sin2ty = \sin 2t.

Find the gradient of the tangent to the curve at the point when t=0t = 0.

*You must use calculus and show any derivatives that you need to find when solving this problem.*
Excellence
Find the values of aa and bb such that the curve y=axbx21y = \dfrac{ax-b}{x^2-1} has a turning point at (3,1)(3,1).

*You must use calculus and show any derivatives that you need to find when solving this problem.*
Achievement
Differentiate y=2(x24x)5y = 2(x^2 - 4x)^5.

*You do not need to simplify your answer.*
Achievement
The percentage of seeds germinating depends on the amount of water applied to the seedbed
that the seeds are sown in, and may be modelled by the function:

P(w)=96ln(w+1.25)16w12P(w) = 96\ln(w + 1.25) - 16w - 12

where PP is the percentage of seeds that germinate and
ww is the daily amount of water applied (litres per square metre of seedbed), with 0w150 \le w \le 15.

Find the amount of water that should be applied daily to maximise the percentage of seeds
germinating.

*You must use calculus and show any derivatives that you need to find when solving this
problem.*
The tangent to the curve y=xy = \sqrt{x} is drawn at the point (4,2)(4,2).
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Find the co-ordinates of the point Q where the tangent intersects the xx-axis.

*You must use calculus and show any derivatives that you need to find when solving this problem.*
Find the coordinates of the point P (x,y)(x,y) on the curve y=xy = \sqrt{x} that is closest
to the point (4,0)(4,0).
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*You do not need to prove that your solution is the minimum value.*

*You must use calculus and show any derivatives that you need to find when solving this
problem.*
Excellence
A rectangle is inscribed in a semi-circle of radius rr, as shown below.
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Show that the maximum possible area of such a rectangle occurs when x=r2x = \dfrac{r}{\sqrt{2}}.

*You do not need to prove that your solution gives the maximum area.*

*You must use calculus and show any derivatives that you need to find when solving this
problem.*
Achievement
Differentiate y=xln(3x1)y = x\ln(3x - 1).

*You do not need to simplify your answer.*
Achievement
Find the gradient of the curve y=1x1x2y = \frac{1}{x} - \frac{1}{x^2} at the point (2,14)\left(2, \frac{1}{4}\right).

*You must use calculus and show any derivatives that you need to find when solving this
problem.*