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1. Find when y = x 5 + x 2 (1) __________________________________________________________________________________________ __________________________________________________________________________________________ 2. Find when y = 6x 3 + 5x -2 (1) __________________________________________________________________________________________ __________________________________________________________________________________________ 3. Find when y = 3x -1 โ€“ 5 โˆ’ 3 2 (1) __________________________________________________________________________________________ __________________________________________________________________________________________ 4. Find when y = (x + 1)(x + 6) (2) __________________________________________________________________________________________ __________________________________________________________________________________________ 5. Find when y = โˆš (โˆ’ 4) (2) __________________________________________________________________________________________ __________________________________________________________________________________________ 6. Find when y = 5+โˆš 2 (2) __________________________________________________________________________________________ __________________________________________________________________________________________ A-Level Starter Activity Topic: Differentiation Chapter Reference: Pure 1, Chapter 12 8 minutes

A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

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Page 1: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

1. Find ๐‘‘๐‘‘๐‘‘๐‘‘

๐‘‘๐‘‘๐‘‘๐‘‘ when y = x5 + x2 (1)

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2. Find ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

when y = 6x3 + 5x-2 (1) __________________________________________________________________________________________

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3. Find ๐‘‘๐‘‘๐‘‘๐‘‘

๐‘‘๐‘‘๐‘‘๐‘‘ when y = 3x-1 โ€“ 5๐‘ฅ๐‘ฅโˆ’

32 (1)

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4. Find ๐‘‘๐‘‘๐‘‘๐‘‘

๐‘‘๐‘‘๐‘‘๐‘‘ when y = (x + 1)(x + 6) (2)

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5. Find ๐‘‘๐‘‘๐‘‘๐‘‘

๐‘‘๐‘‘๐‘‘๐‘‘ when y = โˆš๐‘ฅ๐‘ฅ(๐‘ฅ๐‘ฅ โˆ’ 4) (2)

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6. Find ๐‘‘๐‘‘๐‘‘๐‘‘

๐‘‘๐‘‘๐‘‘๐‘‘ when y = 5+โˆš๐‘‘๐‘‘

๐‘‘๐‘‘2 (2)

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A-Level Starter Activity

Topic: Differentiation Chapter Reference: Pure 1, Chapter 12

8 minutes

Page 2: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

Solutions

1. y = x5 + x2 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 5x4 + 2x M1

2.

y = 6x3 + 5x-2 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 12x2 โ€“ 10x-3 M1

3.

y = 3x-1 โ€“ 5๐‘ฅ๐‘ฅโˆ’32

๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= -3x-2 + 152๐‘ฅ๐‘ฅโˆ’

52

M1

4.

y = (x + 1)(x + 6) y = x2 + 7x + 6 M1 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 2x + 7 M1 5.

y = โˆš๐‘ฅ๐‘ฅ(๐‘ฅ๐‘ฅ โˆ’ 4) y = x1.5 โ€“ 4x0.5 M1 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 1.5x0.5 โ€“ 4x-1.5 M1 6.

y = 5+โˆš๐‘‘๐‘‘๐‘‘๐‘‘2

y = 5x-2 + x-1.5 M1

๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= โˆ’10x-3 -1.5x-2.5 M1

Page 3: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

1. Find the value of the gradient of the curve y = 3x2 + x โ€“ 5 at the point x = 1 (2) __________________________________________________________________________________________

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2. Find the value of the gradient of the curve y = (x + 1)2 at the point (4, 25) (2) __________________________________________________________________________________________

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3. Find the value of the gradient of the curve y = 8๐‘ฅ๐‘ฅ+๐‘ฅ๐‘ฅ

3

4โˆš๐‘ฅ๐‘ฅ (2)

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4. Find the equation of the tangent to the curve y = 3 โ€“ x2 at the point (-3, -6) (4) __________________________________________________________________________________________

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A-Level Starter Activity

Topic: Differentiation Chapter Reference: Pure 1, Chapter 10

10 minutes

Page 4: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

Solutions

1. y = 3x2 + x โ€“ 5 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= 6๐‘ฅ๐‘ฅ + 1 M1

At x = 1, ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= 6(1) + 1 = 7 M1

2.

y = (x + 1)2 = (x + 1)(x + 1) y = x2 + 2x + 1 M1 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= 2๐‘ฅ๐‘ฅ + 2 M1 When x = 4, ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= 2(4) + 2 = 10 M1

3.

y = 8๐‘ฅ๐‘ฅ+๐‘ฅ๐‘ฅ3

4โˆš๐‘ฅ๐‘ฅ = 8๐‘ฅ๐‘ฅ

4๐‘ฅ๐‘ฅ12

+ ๐‘ฅ๐‘ฅ3

4๐‘ฅ๐‘ฅ12 = 2x0.5 + 1

4๐‘ฅ๐‘ฅ2.5 M1

๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= x-0.5 + 58x1.5 M1

4.

y = 3 โ€“ x2

๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= โˆ’2๐‘ฅ๐‘ฅ M1

When x = -3, ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= โˆ’2(โˆ’3) = 6 M1

Equation of line crossing (-3, -6) -6 = 6(-3) + c -6 = -18 + c c = 12

M1

y = 6x + 12 M1

Page 5: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

1. Find ๐‘‘๐‘‘๐‘‘๐‘‘

๐‘‘๐‘‘๐‘‘๐‘‘ of the curve, y = x2 + 4x + 6 (1)

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2. Find ๐‘‘๐‘‘๐‘‘๐‘‘

๐‘‘๐‘‘๐‘‘๐‘‘ of the curve, y = 2x2 - 5x - 2 (1)

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3. Find ๐‘‘๐‘‘๐‘‘๐‘‘

๐‘‘๐‘‘๐‘‘๐‘‘ of the curve, y = (x + 5)(4x - 2) (2)

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4. Find ๐‘‘๐‘‘๐‘‘๐‘‘

๐‘‘๐‘‘๐‘‘๐‘‘ of the curve, y = (-9x + 3)(2x - 4) (2)

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5. Find the values of x for which ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 0 when y = (x - 3)(x + 5) (4)

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A-Level Starter Activity

Topic: Differentiating Quadratics Chapter Reference: Pure 1, Chapter 12

6 minutes

Page 6: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

Solutions

1. y = x2 + 4x + 6 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 2๐‘ฅ๐‘ฅ + 4 M1

2.

y = 2x2 - 5x โ€“ 2 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 4๐‘ฅ๐‘ฅ โˆ’ 5 M1

3.

y = (x + 5)(4x - 2) y = x2 + 18x - 10 M1 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 2๐‘ฅ๐‘ฅ + 18 M1 4.

y = (-9x + 3)(2x - 4) y = -18x2 + 42x - 12 M1 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= โˆ’36๐‘ฅ๐‘ฅ + 42 M1 5.

๐‘ฆ๐‘ฆ = (๐‘ฅ๐‘ฅ โˆ’ 3)(๐‘ฅ๐‘ฅ + 5) y = x2 + 2x โ€“ 15 M1 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 2๐‘ฅ๐‘ฅ + 2 M1 2x + 2 = 0 2x = -2 M1

x = -1 M1

Page 7: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

1. A curve has the equation y = 2 + 4

๐‘ฅ๐‘ฅ.

a. Find an equation of the normal to the curve at the point M (4, 3). The normal to the curve at M intersects the curve again at the point N. b. Find the coordinates of the point N. (3) __________________________________________________________________________________________

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2. A curve has the equation y = (x + 2)(x โ€“ 5) a. Find an equation of the normal to the curve at the point P(2, -12). (3) __________________________________________________________________________________________

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A-Level Starter Activity

Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12

7 minutes

Page 8: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

Solutions

1a. y = 2 + 4

๐‘ฅ๐‘ฅ

๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= โˆ’4๐‘ฅ๐‘ฅ-2 M1

Gradient at M = -14

Gradient of normal = 4 M1

y โ€“ 3 = 4(x โ€“ 4) y = 4x โ€“ 13 M1

1b.

4x โ€“ 13 = 2 + 4๐‘ฅ๐‘ฅ

4x2 โ€“ 15x โ€“ 4 = 0 M1

(4x + 1)(x โ€“ 4) = 0 M1 x = 4 (at M) x = โˆ’1

4

Therefore, N(-14

,โˆ’14) M1

2.

y = (x + 2)(x โ€“ 5) y = x2 -3x - 10 M1 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= 2๐‘ฅ๐‘ฅ โˆ’ 3 M1 At x = 2, ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= 2(2) โˆ’ 3 = 1 Therefore, gradient of normal = -1

M1

y - -12 = -1(x โ€“ 2) y + 12 = -x + 2 y = -x โ€“ 10

M1

Page 9: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

1. The point A lies on the curve y = 12

๐‘ฅ๐‘ฅ2 and the x-coordinate of A is 2.

a. Find an equation of the tangent to the curve at A. Give your answer in the form ax + by + c = 0, where a, b and c, are integers. (3) b. Verify that the points where the tangent at A intersects the curve again has the coordinates (-1, 12). (3) __________________________________________________________________________________________

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2. The curve C has the equation y = x โ€“ 3๐‘ฅ๐‘ฅโˆ’

12 + 3 and passes through the point P (4, 1). Show that the tangent to C

at P passes through the origin. (3) __________________________________________________________________________________________

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A-Level Starter Activity

Topic: Differentiation and Tangents Chapter Reference: Pure 1, Chapter 12

7 minutes

Page 10: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

Solutions

1a. ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= โˆ’24๐‘ฅ๐‘ฅ-3 M1 At A, y = 3, gradient = -3 M1 y โ€“ 3 = -3(x โ€“ 2) 3x + y โ€“ 9 = 0 M1

1b.

Tangent: x = -1, -3 + y โ€“ 0 = 0 y = 12

M1

For the curve, x = -1, y = 12

1 = 12 M1

Therefore, tangent intersects curve at (-1, 12) M1 2.

๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= 1 โˆ’ 32๐‘ฅ๐‘ฅโˆ’

12

Gradient at P = 14

M1

y โ€“ 1 = 14

(๐‘ฅ๐‘ฅ โˆ’ 4) M1 y = ยผ x which passes through (0,0) M1

Page 11: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

1. Find the set of values of x for which f(x) is increasing when, f(x) = 2x2

+ 2x + 1 (3) __________________________________________________________________________________________

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2. Find the set of values of x for which f(x) is decreasing when f(x) = x(x โ€“ 6)2 (4) __________________________________________________________________________________________

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3. f(x) = x3 + kx2 + 3 Given that (x + 1) is a factor of f(x) a. Find the values of the constant k, (2) b. Find the set of values of x for which f(x) is increasing. (3) __________________________________________________________________________________________

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A-Level Starter Activity

Topic: Increasing and Decreasing Functions Chapter Reference: Pure 1, Chapter 12

8 minutes

Page 12: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

Solutions

1. fโ€™(x) = 4x + 2 M1 4x + 2 โ‰ฅ 0 M1 x โ‰ฅ -1

2 M1

2.

f(x) = x(x โ€“ 6)2

f(x) = x(x2 โ€“ 12x +36) f(x) = x3 โ€“ 12x2 + 36x

M1

fโ€™(x) = 3x2 โ€“ 24x + 36 M1 3x2 โ€“ 24x + 36 โ‰ค 0 x2 โ€“ 8x + 12 โ‰ค 0 M1

(x โ€“ 6)(x โ€“ 2) โ‰ค 0 2 โ‰ค x โ‰ค 6 M1

3a.

As (x + 1) is a factor, f(-1) = 0 M1 Therefore, -1 + k + 3 = 0 k = -2

M1

3b.

fโ€™(x) = 3x2 โ€“ 4x M1 3x2 โ€“ 4x โ‰ฅ 0 x(3x โ€“ 4) โ‰ฅ 0 M1

x โ‰ค 0 and x โ‰ฅ 4

3 M1

Page 13: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

1. The graph shows the height, h cm of letters on a website advert t seconds after the advert appears on the screen.

For t in the interval 0 โ‰ค t โ‰ค 2, h is given by the equation,

H = 2t4 โ€“ 8t3 + 8t2 + 1

For larger values of t, the variation of h over this interval is repeated every 2 seconds. a. Find ๐‘‘๐‘‘โ„Ž

๐‘‘๐‘‘๐‘‘๐‘‘ for t in the interval 0 โ‰ค t โ‰ค 2 (1)

b. Find the rate at which the maximum height of the letters is increasing when t = 0.25. (1) c. Find the maximum height of the letters. (3) __________________________________________________________________________________________

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A-Level Starter Activity

Topic: Modelling with Differentiation Chapter Reference: Pure 1, Chapter 12

5 minutes

Page 14: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

Solutions

1a. ๐‘‘๐‘‘โ„Ž๐‘‘๐‘‘๐‘‘๐‘‘

= 8๐‘ก๐‘ก3 โ€“ 24t2 + 16t M1 1b.

When t = 0.25, ๐‘‘๐‘‘โ„Ž๐‘‘๐‘‘๐‘‘๐‘‘

= 2.625 cm per second. M1

1c.

Stationary point: 8t3 โ€“ 24t2 + 16t = 0 M1

8t(t โ€“ 1)(t โ€“ 2) = 0 t = 0 t = 1 t = 2

M1

From graph, maximum occurs when t = 1, Therefore, maximum height is 3 cm. M1

Page 15: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

1. Find ๐‘‘๐‘‘

2๐‘ฆ๐‘ฆ๐‘‘๐‘‘๐‘ฅ๐‘ฅ2

when y = x3 โ€“ 6x2 โ€“ 36x + 15 (2) __________________________________________________________________________________________

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2. Find the stationary points of y = ๐‘ฅ๐‘ฅ

4+162๐‘ฅ๐‘ฅ2

and state if it is a maximum or minimum. (6) __________________________________________________________________________________________

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A-Level Starter Activity

Topic: Second Order Derivatives Chapter Reference: Pure 1, Chapter 12

8 minutes

Page 16: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

Solutions

1a. ๐‘‘๐‘‘๐‘ฆ๐‘ฆ๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= 3๐‘ฅ๐‘ฅ2 โ€“ 12x โ€“ 36 M1 ๐‘‘๐‘‘2๐‘ฆ๐‘ฆ๐‘‘๐‘‘๐‘ฅ๐‘ฅ2

= 6x โ€“ 12 M1 1b.

y = 12๐‘ฅ๐‘ฅ2 + 8๐‘ฅ๐‘ฅ-2 M1

๐‘‘๐‘‘๐‘ฆ๐‘ฆ๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= ๐‘ฅ๐‘ฅ โˆ’ 16๐‘ฅ๐‘ฅ-3

At stationary point, ๐‘‘๐‘‘๐‘ฆ๐‘ฆ๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= 0 M1

๐‘ฅ๐‘ฅ โˆ’ 16๐‘ฅ๐‘ฅ-3 = 0 x4 = 16 x = ยฑ 2

M1

๐‘‘๐‘‘2๐‘ฆ๐‘ฆ๐‘‘๐‘‘๐‘ฅ๐‘ฅ2

= 1 + 48x-4 M1

At (-2, 4), ๐‘‘๐‘‘2๐‘ฆ๐‘ฆ

๐‘‘๐‘‘๐‘ฅ๐‘ฅ2 = 1 + 48(-2)-4 = 4

Therefore, minimum point M1

At (2, 4), ๐‘‘๐‘‘2๐‘ฆ๐‘ฆ

๐‘‘๐‘‘๐‘ฅ๐‘ฅ2 = 1 + 48(2)-4 = 4

Therefore, minimum point M1

Page 17: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

1. Complete the table:

Curve ๐’…๐’…๐’…๐’…๐’…๐’…๐’…๐’…

y = x5

f(x) = 2x3

f(x) = x-3

y = 5x-8

y = 4x3 + 3x-4

f(x) = 2x + 13๐‘ฅ๐‘ฅ6

f(x) = 7 + ๐‘ฅ๐‘ฅโˆ’45

y = 3x-1 - 5๐‘ฅ๐‘ฅโˆ’32

f(x) = 2 โ€“ 7x-1 + ๐‘ฅ๐‘ฅโˆ’83

y = 14๐‘ฅ๐‘ฅโˆ’ 1

๐‘ฅ๐‘ฅ2

(10)

A-Level Starter Activity

Topic: Simple Differentiation Chapter Reference: Pure 1, Chapter 12

7 minutes

Page 18: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

Solutions

Curve ๐’…๐’…๐’…๐’…๐’…๐’…๐’…๐’…

y = x5 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= 5๐‘ฅ๐‘ฅ4 M1

f(x) = 2x3 fโ€™(x) = 6x2 M1

f(x) = x-3 fโ€™(x) -3x-4 M1

y = 5x-8 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= -40x-9 M1

y = 4x3 + 3x-4 ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= 12x2 โ€“ 12x-5 M1

f(x) = 2x + 13๐‘ฅ๐‘ฅ6 fโ€™(x) = 2 + 2x5 M1

f(x) = 7 + ๐‘ฅ๐‘ฅโˆ’45 fโ€™(x) = -4

5๐‘ฅ๐‘ฅโˆ’1.8 M1

y = 3x-1 - 5๐‘ฅ๐‘ฅโˆ’32

๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘ฅ๐‘ฅ

= โˆ’3๐‘ฅ๐‘ฅ-2 + 152๐‘ฅ๐‘ฅ-2.5 M1

f(x) = 2 โ€“ 7x-1 + ๐‘ฅ๐‘ฅโˆ’83 fโ€™(x) = 7x-2 - 8

3๐‘ฅ๐‘ฅโˆ’

113 M1

y = 14๐‘ฅ๐‘ฅโˆ’ 1

๐‘ฅ๐‘ฅ2 ๐‘‘๐‘‘๐‘‘๐‘‘

๐‘‘๐‘‘๐‘ฅ๐‘ฅ= -4x-2 + 2x-3 M1

Page 19: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

1. The curve y = x3 โ€“ 3x + 1 is stationary at the points P and Q. a. Find the coordinates of the points P and Q. (4) b. Find the length of PQ in the form kโˆš5 (2) __________________________________________________________________________________________

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2a. Find the coordinates of the stationary points on the curve, y = 2 + 9x + 3x2 โ€“ x3 (4) b. Determine whether each stationary point is a maximum or minimum point. (3) __________________________________________________________________________________________

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A-Level Starter Activity

Topic: Stationary Points Chapter Reference: Pure 1, Chapter 12

8 minutes

Page 20: A-Level Topic: Differentiation 8 Starter Activity Chapter ......Topic: Differentiation and Normals Chapter Reference: Pure 1, Chapter 12 7 minutes Solutions 1a. y = 2 + 4 ๐‘ฅ๐‘ฅ

Solutions

1a. ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 3๐‘ฅ๐‘ฅ2 โ€“ 3

At stationary point, ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 0 M1

3๐‘ฅ๐‘ฅ2 โ€“ 3 = 0 x2 = 1 x = ยฑ 1

M1

When x = 1, y = -1 M1

When x = -1, y = 3 M1

1b.

PQ2 = 22 + 42 = 20 M1 PQ = โˆš20 = 2โˆš5 M1

2a.

๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 9 + 6๐‘ฅ๐‘ฅ โˆ’ 3x2

At stationary point, ๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘

= 0 M1

9 + 6๐‘ฅ๐‘ฅ โˆ’ 3x2 = 0 -3(x+1)(x โ€“ 3) = 0 x = -1, 3

M1

When x = -1, y = -3 M1

When x = 3 y = 29 M1

(-1, -3) and (3, 29) 2b.

๐‘‘๐‘‘2๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘2

= 6 โˆ’ 6๐‘ฅ๐‘ฅ M1 At (-1, -3), ๐‘‘๐‘‘2๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘2

= 6 โˆ’ 6(โˆ’1) = 12 Therefore, minimum point

M1

At (3, 29), ๐‘‘๐‘‘2๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘๐‘‘2

= 6 โˆ’ 6(3) = -12 Therefore, maximum point

M1