topic badge

4.02 Using the first derivative

Worksheet
Increasing, decreasing, and stationary points
1

Consider the given graph of the function

f \left( x \right) = - \left(x - 4\right)^{3} + 7:

a

State the x-coordinate of the stationary point.

b

State the domain for which f \left( x \right) is decreasing.

1
2
3
4
5
6
7
8
x
-1
1
2
3
4
5
6
7
8
9
y
2

For each of the following functions graphed below:

i

State the x-coordinate of the stationary point(s).

ii

State the domain for which f \left( x \right) is increasing.

iii

State the domain for which f \left( x \right) is decreasing.

a
-5
-4
-3
-2
-1
1
2
3
4
5
x
-5
-4
-3
-2
-1
1
2
3
4
5
y
b
-5
-4
-3
-2
-1
1
2
3
4
5
x
-5
-4
-3
-2
-1
1
2
3
4
5
y
c
-12
-10
-8
-6
-4
-2
2
4
6
x
-4
-2
2
4
6
8
y
d
-7
-6
-5
-4
-3
-2
-1
1
2
3
4
5
x
-7
-6
-5
-4
-3
-2
-1
1
2
3
y
3

Consider the given graph of the function f \left( x \right):

a

State the x-coordinate of the stationary point.

b

State the domain for which f \left( x \right) is increasing.

c

State the domain for which f \left( x \right) is decreasing.

d

State the domain for which f \left( x \right) is constant.

-7
-6
-5
-4
-3
-2
-1
1
2
3
x
-5
-4
-3
-2
-1
1
2
3
4
5
y
4

Find the stationary point(s) for the following functions:

a

y=x^2-2x+3

b

y=6+4x-x^2

c

y=2x^3+9x^2-24x+1

d

y=x^3+3x^2+3x-6

e

y=x^2+2x-3

f

y=-x^2+6x-2

g

y=x^4-2x^2

5

Show that the following curves have no stationary points:

a

y=\dfrac{x}{x-1}

b

y=x\sqrt{x-1}

c

y=\dfrac{x}{\sqrt{x+1}}

d

y=3x-\dfrac{4}{x+2}

Types of stationary points
6

Determine whether following statements describe a maximum or a minimum turning point:

a

A point where the curve changes from increasing to decreasing.

b

A point where the curve changes from decreasing to increasing.

7

For each of the following functions:

i

Find the derivative.

ii

Find the stationary point(s).

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

8

For each of the following quadratic equations:

i

Find the stationary point(s).

ii

Classify each stationary point.

a
y = x^{2} - 4 x + 6
b
y = 5 + x - x^{2}
c
y = 2 x^{2} - 8 x + 7
d
f \left( x \right) = 3 x^{2} - 54 x + 241
e

y=x^2+4x-2

f

y=-2x^2+8x+1

g

y=x^3-x^2-8x+1

h

y=x^3+5x^2+8x-4

i

y=x^4-8x^2

j

y=x^4-4x^3

k

y=x^2(x-1)^4

l

y=\dfrac{2x}{x^2+1}

m

y=3x+\dfrac{12}{x+1}

9

The function y = a x^{2} - b x + c passes through the points (5, - 42) and (4, - 66) and has a maximum turning point at x = 3. Find the following:

a

\dfrac{dy}{dx}

b

a

c

c

d

b

10

Consider the cubic function y = x^{3} - a x^{2} + b x + 11, which has stationary points at x=2 and x=10. Find the following:

a

\dfrac{dy}{dx}

b

a

c

b

Graphs of functions
11

Consider the equation of the parabola y = 3 x^{2} - 18 x + 24.

a

Find the x-intercepts.

b

Find the y-intercept.

c

Find \dfrac{dy}{dx}.

d

Find the stationary point.

e

Classify the stationary point.

f

Sketch the graph of the parabola.

12

Sketch the linear function for which f \left( 0 \right) = 1 and f' \left( 2 \right) = 3.

13

Sketch the quadratic function, f \left( x \right), that satisfies the following conditions:

a
  • f \left( 0 \right) = - 18
  • f \left( 3 \right) = 0
  • f \left( 6 \right) = 6
  • f' \left( 6 \right) = 0
  • f' \left( x \right) > 0 for x < 6

b
  • f \left( 0 \right) = 16
  • f \left( 2 \right) = 0
  • f \left( 5 \right) = - 9
  • f' \left( 5 \right) = 0
  • f' \left( x \right) < 0 for x < 5

c
  • f \left( 0 \right) = 5
  • f \left( - 2 \right) = 0
  • f' \left( 3 \right) = 0
  • f' \left( x \right) > 0 for x < 3

14

Sketch a cubic function, f \left( x \right), that satisfies the following conditions:

a
  • f' \left( - 5 \right) = 0
  • f' \left( x \right) > 0 for all other values of x.

b
  • f \left( 0 \right) = 7
  • f \left( - 2 \right) = 0
  • f \left( - 4 \right) = - 1
  • f' \left( - 4 \right) = 0
  • f' \left( x \right) > 0 for x < - 4

  • f' \left( x \right) > 0 for x > - 4

c
  • f' \left( 2 \right) = 0
  • f' \left( - 3 \right) = 0
  • f' \left( x \right) < 0 for - 3 < x < 2

  • f' \left( x \right) > 0 elsewhere

15

Sketch a quartic function, f \left( x \right), that satisfies the following conditions:

a
  • f' \left( - 1 \right) = 0
  • f' \left( 4 \right) = 0
  • f' \left( x \right) > 0 for x > 4
  • f' \left( x \right) < 0 elsewhere
  • b
  • f \left( 0 \right) = 0
  • f' \left( 0 \right) = 0
  • f' \left( 2 \right) = 0
  • f' \left( - 2 \right) = 0
  • f' \left( x \right) > 0 for x < - 2, 0 < x < 2
  • f' \left( x \right) < 0 elsewhere
  • 16

    Consider the given graph of the gradient function f' \left( x \right) = 2 x + 6:

    a

    State the x-intercept of the gradient function.

    b

    Is the gradient of f \left( x \right) for x > - 3 positive or negative?

    c

    Is the gradient of f \left( x \right) for x < - 3 positive or negative?

    d

    State the feature of f \left( x \right) that this x-intercept represent.

    -4
    -3
    -2
    -1
    1
    2
    3
    4
    x
    -4
    -3
    -2
    -1
    1
    2
    3
    4
    f'(x)
    17

    The function f \left( x \right) has a derivative given by f' \left( x \right) = 6 \left(x - 2\right) \left(x - 7\right). A graph of the derivative function is shown:

    a

    State the x-intercept(s) of the gradient function.

    b

    State the kind of feature at the point \left(2, 77\right) on the graph of f \left( x \right).

    c

    State the kind of feature at the point \left(7, - 48 \right) on the graph of f \left( x \right).

    -8
    -6
    -4
    -2
    2
    4
    6
    8
    x
    -40
    -30
    -20
    -10
    10
    20
    30
    40
    f'(x)
    18

    The function f \left( x \right) has a derivative given by f' \left( x \right) = 3 \left(x + 5\right)^{2}. A graph of the derivative function is shown:

    a

    State the x-intercept of the gradient function.

    b

    State the kind of feature at the point \left( - 5 , 2\right) on the graph of f \left( x \right).

    -8
    -6
    -4
    -2
    2
    4
    6
    8
    x
    -8
    -6
    -4
    -2
    2
    4
    6
    8
    f'(x)
    19

    Consider the gradient function f' \left( x \right) = 12 \left(x + 4\right)^{2} \left(x + 7\right).

    a

    Graph the gradient function.

    b

    State the kind of feature at the point \left( - 7 , - 1617 \right) on the graph of f \left( x \right).

    c

    State the kind of feature at the point \left( - 4 , - 1536 \right) on the graph of f \left( x \right).

    Sign up to access Worksheet
    Get full access to our content with a Mathspace account

    Outcomes

    MA12-3

    applies calculus techniques to model and solve problems

    MA12-6

    applies appropriate differentiation methods to solve problems

    What is Mathspace

    About Mathspace