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iGCSE (2021 Edition)

26.05 Stationary points (Extended)

Worksheet
Stationary points
1

State the type of point that matches the following descriptions:

a

A point where the curve changes from decreasing to increasing.

b

A point where the curve changes from increasing to decreasing.

c

A point where the tangent is horizontal and the concavity changes about the point.

2

For each of the following functions:

i

Find the derivative.

ii

Find the coordinates of any stationary points.

iii

Classify each stationary point.

a
y = - 6 x^{2} + 84 x - 29
b
y = x^{3} - 21 x^{2} + 144 x - 19
c
f \left( x \right) = \left(x + 3\right)^{2} \left(x + 6\right)
d
f \left( x \right) = \left(x + 5\right)^{3} + 4
e
f \left( x \right) = - \dfrac{x^{3}}{3} + \dfrac{13 x^{2}}{2} - 30 x + 10
f
f \left( x \right) = \left( 4 x + 5\right) \left(x + 1\right)
g

f \left( x \right) = 134 - 300 x + 240 x^{2} - 64 x^{3}

h

f \left( x \right) = \left(x^{2} - 9\right)^{2} + 4

3

Consider the parabola with equation y = 5 + x - x^{2}.

a

Find the coordinates of the vertex of the parabola.

b

State the gradient of the tangent to the parabola at the vertex.

c

What type of stationary point is at the vertex of this parabola?

4

Consider the function f \left( x \right) = x^{2} + 4 x + 9.

a

Find an equation for the gradient function f' \left( x \right).

b

State the interval in which the function is increasing.

c

State the interval in which the function is decreasing.

d

Find the coordinates of the stationary point.

e

Classify the stationary point.

5

Consider the function f \left( x \right) = 4 x^{3} + 5 x^{2} - 4.

a

Find an equation for the gradient function f' \left( x \right).

b

Find the coordinates of the stationary points.

c

Complete the table of values:

x-2-\dfrac{5}{6}-\dfrac{1}{2}01
f'\left( x \right)00
d

Hence determine the:

i

Local minimum

ii

Local maximum

e

Is - 4 the absolute minimum value of the function? Explain your answer.

6

Consider the function f \left( x \right) = 3 x^{2} - 54 x + 241.

a

Find f' \left( x \right).

b

Find the x-coordinate of the stationary point.

c

Classify the stationary point.

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Outcomes

0580E2.13B

Apply differentiation to gradients and turning points (stationary points). Discriminate between maxima and minima by any method.

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