Power of Maths: Paper 1 – Answers
(g) x 2 – 10x + 2 (h) 8x ___
( j) 3x 2 − 2x + 1 __
(c) −3x 2 + 4x ___
3 − 2 __
5 (i) 15x 2 − 6x ___
3 3. (a) –x (b) 4 + 2x ___
5 + 4 __
3
4. (a) 2x + 1 (b) 16x – 2 = 2(8x – 1) (c) 6x2 – 2x – 1 (d) 3t 2 – 1 (e) 18v – 12 = 6(3v – 2) (f ) 1 5. (a) 1 (b) 19 (c) 2 (d) 3x2 – 8x + 5; 6x – 8 (e) 51; –38 (f ) 60; – 46 6. (a) –2 (b) m = –1; x + y + 3 = 0 (c) m = 10; 10x – y + 2 = 0 7. 3
5 − 1 (d) – 4(1 + 3x 2) (e) 1 − 2x ______
3 − 3x 2 5
0·6 N/m per sec 8. (a) 1 (b) ± 2 (c) –1, 2 9. (a) 9∙2 °C (b) 28∙1 °C (c) Midnight (d) –1∙67°/hr (e) Midday (Noon) 10. 36π m3/m 11. (a) –20 (b) –10 (c) a = –9, c = 14
_ 5 N/m per sec =
Chapter 21 Exercise 3 1. (a) 3 (b) 1 (c) 10 (d) 6 (e) − 1
Exercise 6
1. (a) L Min (2, –2) (i) 0∙6, 3∙4 (ii) 0·6 < x < 3·4, x ∈ R (iii) 0 ≤ x ≤ 2, x ∈ R (b) x = 2 (c) 2x – y – 7 = 0 2. (a) L Min
( 1 __
2 , − 25 ___
4 ) (b) (i) –2 ≤ x ≤ 3, x ∈ R
(ii) No points of intersection of y = –8 and the curve (iii) No, based on answer to (ii) 3. b = –2, c = –3
4. (a) f ′(x) = –5 – 4x; L Max
( − 5 __
4 , 49 ___
8
) (b) –3, 1 _
2
(d) –2·2, 0·7 5. (a) (0, 0) L Max; (4, –32) L Min (b) (0, 0) (6, 0) (d) 0 < x < 4, x ∈ R 6. (a) 3x2 – 6x; (0, 0) L Max; (2, – 4) L Min (c) (i) x = –0·7, 1, 2·7 (ii) 0 < x < 2, x ∈ R 7. (a) f (–1) = –3; f (3) = 1 (b) 3x2 – 6x (c) (0, 1) L Max; (2, –3) L Min (e) (i) 0∙7 < x < 2∙9, x ∈ R (ii) 0 < x < 2, x ∈ R 8. (a) x –1·5 –1 023 3·5 –9 0 3 –9 0 13·5
y
(b) 15x – y + 4 = 0 (c) 5x – y – 10 = 0 (d) 77x – y + 86 = 0 (e) 12x – y + 20 = 0 3. (a) (–1, 1) (b) (2, – 4) (c) (3, 1) (d) (1, – 6) 4. (a) (1, –1) (b) (–1, – 6) (c) (–1, 0), (2, –9) (d) (–2, –3), (1, 0) 5. (a) (2, 13) (b) (–3, 13),
(2, –82) (c) ( −2, − 9),
( − 2 __
3 , − 239 ____
(e) (x1, y1) = (0, 12), (x2, y2) = (4, – 20) Exercise 4
4. x < 0, x ∈ R 5. x > 4, x ∈ R 6. (a) Increasing (b) Increasing (c) Decreasing; accelerating at t = 1, 2 and decelerating at t = 3 7. (a) Increasing (b) Increasing (c) Decreasing (d) Decreasing 8. (a) Increasing (b) Increasing (c) Decreasing
Exercise 5
1. (a) (2, 1) L Min (b) (3, 22) L Max (c) (–1, 2) L Max; (3, –30) L Min (d) (1, 6) L Min; (2, 7) L Max (e) (–2, 3) L Min; (0, 7) L Max 2. 15
3. (
− b ___
2a , 4ac − b2 _______
4a ) 4. (a) (i) (–1, 0) (ii) (3, 5)
(b) (i) 5 (ii) 0 5. (–1, 0) L Max; (2, –54) L Min (a) A (–2, –22); B (–1, 0); C (0, –14); D (2, –54);
E (3, –32) (b) L Max (c) L Min (d) –1 < x < 2, x ∈ R (e) 0 (f ) –54 6. (a) 2x + p, – 6 (b) 8 – 4x (i) (0, 3) (ii) 11 (iii) x < 1, x ∈ R (c) k = 3; (1, 3) (d) k = 12; (–2, 23) L Max; (2, –9) L Min (e) k = 4; (–2, 32) L Max; (2, 0) L Min (f ) a = 2, b = –24, c = 3 (g) k = –9; (–1, 6) L Max; (3, –26) L Min 7. 93∙75 cm; 10∙38 a.m. 8. (a) (i) 40 m (ii) 400 m (b) (i) 40 (ii) – 40
_ 4 2. (a) x + y – 4 = 0
(b) 6x 2 – 10x – 4 (c)
( − 1 __
3 , 100 ____
(f ) x = –1∙1, 0∙4, 3∙1 9. 1 __
27 ) L Max; (2, –9) L Min 2 × 2x (a) Curve does not
cross the x-axis (b) 2·6 10. (a) (0, 0) L Min (c) – 0·8, 2 27 ) (d) (3, –15)
Exercise 7 1. (a) Increasing at €14 per year (b) Increasing at €4 per year (c) Decreasing at €10 per year 2. (a) Increasing at 2 eagles per year (b) Increasing at 8 eagles per year 3. (a) Increasing at €55 000 per year (b) Increasing at €31 000 per year (c) Increasing at €40 000 per year 4. (a) Increasing at €2400 per day (b) Increasing at €1200 per day 5. (a) 16·33 l (b) –13·06 l/min (c) –13·06 l/min 6. (a) 3 m/s (b) 4 m/s2 (c) 20 s, 860 m 7. (a) 77 + 26t – 3t 2 (b) 26 – 6t (c) 11 s (d) 132 m/s (e) 8 m/s2 8. (a) 160 m/s (b) –10 m/s2 (c) 2100 m
Exercise 8
1. (a) 10 – x (b) 10x – x2 (c) 25 m2 2. (a) (i) 20 – 2x (ii) 4000x – 400x2 (b) 5 cm 3. (a) 64 – x (b) 264 + 62x – x2 (c) 1225 cm2 4. (a) 27 – x (b) 27x2 – x3 (c) 2916 cm3 5. (a) 200 – π h (b) 400h – 2πh2 (c) 100 m
6. (a) − 1 _
(b) dP ___
dx = −x 2 + 44x − 160, d 2P ____
3 x3 + 22x 2 − 160x − 1200 7. (a) –2 + 7t – 3t 2 (b) 7 – 6t (c)
dx 2 = −2x + 44 (c) 40 54 ) L Min;
( 1 __
3 , 523 ____
(2, 12) L Max (d) €12 8. (a) (i) €(150x + 30x2) (ii) €(930x – 100x2) (iii) €(780x – 130x2) (b) 3 9. –36 10. 8·75, 17·5 11. (a) (i) 3t 2 – 12t + 9
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