TOPIC 10
Algebraic Expressions & Manipulation
1. Factorise completely (a) 4x² − 25y²
Answer (a): (2x − 5y)(2x + 5y)
(b) 5ax − 5a² − 2x + 2a
Answer (b): (5a − 2)(x − a)
2. (a) Factorise completely (i) 3x² − 12x
Answer (a)(i): 3x(x − 4)
(ii) x² − xy − 2y²
Answer (a)(ii): (x − 2y)(x + y)
2. (b) Simplify x 2 + 4 x x 2 − 16 x 2 − 16 x 2 + 4 x Answer (b):
x ( x + 4 ) ( x − 4 ) ( x + 4 ) = x x − 4 ( x − 4 ) ( x + 4 ) x ( x + 4 ) = x − 4 x ----------------------------------------------------------------------------------------------------------(a) Remove the brackets and simplify 4(7x − 3) − 3(5x − 4)
= 28x − 12 − 15x + 12 = 13x
Answer (a) -------------------------------------------------------------------------------------------------------
(b) Express as a single fraction in its simplest form
4 3 y − 5 4 y 3 y 4 − 4 y 5
Answer (b) ..................................... 1 12 y 12 y 1
(c) Simplify ( 4 a 2 b ) ( 3 a b 3 )
Answer (c) ..................................... 12 a 3 b 4
4.
(a) Factorise completely 16 a 2 − 6 a 16a^2-6a
Answer (a) ..................................... 2 a ( 8 a − 3 ) 2a(8a-3)
(b) Factorise completely 6 x + 3 x y − 4 y − 8 6x+3xy-4y-8
Answer (b) ..................................... ( 3 x − 4 ) ( y + 2 ) (3x-4)(y+2)
5. Factorise
(a) 4 t 2 − 9 4t^2-9 4 t 2 − 9 ,
Answer (a) ..................................... ( 2 t − 3 ) ( 2 t + 3 ) (2t-3)(2t+3)
(b) 3 x 2 + 5 x − 2 3x^2+5x-2
Answer (b) ..................................... ( 3 x − 1 ) ( x + 2 ) (3x-1)(x+2)
6. Factorise completely
(a) 12 a b 2 − 8 a 2 b 12ab^2-8a^2b
Answer ..................................... 4 a b ( 3 b − 2 a ) 4ab(3b-2a)
(b) 2 x 2 + 3 x − 20 2x^2+3x-20
Answer ..................................... ( 2 x − 5 ) ( x + 4 ) (2x-5)(x+4) ---------------------------------------------------------------------------------------------------------------------------
7. (a) Factorise completely 9 p q − 12 q 2 9pq-12q^2
Answer ..................................... 3 q ( 3 p − 4 q ) 3q(3p-4q)
(b) Factorise completely 8 p x + 4 p y − 6 x − 3 y 8px+4py-6x-3y
Answer ..................................... ( 4 p − 3 ) ( 2 x + y ) (4p-3)(2x+y)
8. Factorise completely 2 x y − 3 x − 10 y + 15 2xy-3x-10y+15
Answer ..................................... ( 2 y − 3 ) ( x − 5 ) (2y-3)(x-5)
9. Factorise completely (a) 12 x 2 − 15 x 3 12x^2-15x^3
Answer ..................................... 3 x 2 ( 4 − 5 x ) 3x^2(4-5x)
(b) x 2 − x − 6 x^2-x-6
Answer ..................................... ( x − 3 ) ( x + 2 ) (x-3)(x+2)
10. (a) Factorise
(i) x 2 + x − 12 x^2+x-12
Answer ..................................... ( x + 4 ) ( x − 3 ) (x+4)(x-3)
(ii) 25 x 2 − 4 y 2 25x^2-4y^2
Answer ..................................... ( 5 x − 2 y ) ( 5 x + 2 y ) (5x-2y)(5x+2y)
(b) Write as a single fraction
4 3 p + 1 6 p \frac{4}{3p}+\frac{1}{6p} 3 p 4 + 6 p 1
Answer ..................................... 3 2 p \dfrac{3}{2p} 2 p 3
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11. Factorise completely
(a) 20p + 25p²
Answer …………… 5p(4 + 5p)
(b) 9 − 4t²
Answer …………… (3 − 2t)
(c) 9 + 35x − 4x²
Answer …………… (9 − x)(4x + 1)
12. Expand the brackets and simplify
(a) 6k − 2(l − k) + 3
Answer …………… 8k − 2l + 3
(b) (2x − 3)(x + 4)
Answer …………… 2x² + 5x − 12
13. Factorise completely
(a) 16p + 4p²
Answer …………… 4p(4 + p)
(b) xy + 2ay + 3ax + 6a²
Answer …………… (x + 2a)(y + 3a)
14. (a) Factorise fully
10x²y + 15xy²
Answer …………… 5xy(2x + 3y)
(b) Factorise 25 a 2 − b 2 25a^2 - b^2
Answer …………… ( 5 a − b ) ( 5 a + b ) (5a - b)(5a + b)
(c) Simplify 3 ( x + 1 ) 2 − 2 x + 1 \dfrac{3}{(x+1)^2} - \dfrac{2}{x+1}
Answer …………… 1 − 2 x ( x + 1 ) 2 \dfrac{1 - 2x}{(x+1)^2}
(d) Simplify 3 a 2 10 b c × 9 a 5 b 2 c \dfrac{3a^2}{10bc} \times \dfrac{9a}{5b^2c}
Answer …………… 27 a 3 50 b 3 c 2 \dfrac{27a^3}{50b^3c^2}
15. (a) Expand and simplify ( t − 5 ) ( t + 3 ) (t - 5)(t + 3) Answer …………… t 2 − 2 t − 15 t^2 - 2t - 15
(b) Factorise 64 x 2 − 9 y 2 64x^2 - 9y^2
Answer …………… ( 8 x − 3 y )
(c) Factorise 6 a b − 2 a − 3 a 2 + 4 b 6ab - 2a - 3a^2 + 4b
Answer …………… ( 3 a − 2 ) ( 2 b − a )
(d) (i) Write x 2 − 6 x + 3 x^2 - 6x + 3 in the form ( x − a ) 2 + b (x - a)^2 + b
Answer …………… ( x − 3 ) 2 − 6 (x - 3)^2 - 6
(ii) Hence solve x 2 − 6 x + 3 = 0 x^2 - 6x + 3 = 0 leaving your answer in the form p ± q p \pm \sqrt{q}
Answer x = x = x = …………… 3 ± 6 3 \pm \sqrt{6}
16. (a) Factorise 25 r 2 − 4 25r^2 - 4 Answer …………… ( 5 r − 2 )
(b) Factorise completely 6 r 2 h − 2 r 2 h 6r^2h - 2r^2h
Answer …………… 2 r 2 h ( 3 r − 1 )
(c) Factorise completely 8 x y + 4 x − 6 y − 3 8xy + 4x - 6y - 3
Answer …………… ( 4 x − 3 ) ( 2 y + 1 ) (4x - 3)(2y + 1)
17. (a) Solve 2 ( 5 p ) = 250 2(5^p) = 250 Answer p = p = p = …………… 3
(b) Simplify
(i) 1 + x − 5 1 + x^{-5}
Answer …………… x 5 + 1 x 5 \dfrac{x^5 + 1}{x^5}
(ii) 3 a 4 × 9 a 2 8 \dfrac{3a}{4} \times \dfrac{9a^2}{8}
Answer …………… 27 a 3 32 \dfrac{27a^3}{32}
18. (a) Expand and simplify (i) 4 ( 2 t + 3 ) + 5 4(2t + 3) + 5
Answer …………… 8 t + 17 8t + 17
(ii) 6 p + 3 q − 2 ( 2 p − 5 q ) 6p + 3q - 2(2p - 5q)
Answer …………… 2 p + 13 q 2p + 13q
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(b) Factorise completely
25x²y² − 15x²y
Answer 5x²y(5y − 3)
19. (a) Expand and simplify (2x + 1)(x + 4).
Answer 2x² + 9x + 4
(b) Write 3 x + 4 x + 2 \dfrac{3}{x} + \dfrac{4}{x+2} as a single fraction in its simplest form.
Answer 7 x + 6 x ( x + 2 ) \dfrac{7x + 6}{x(x + 2)}
(c) Solve 10 x = x + 3 \dfrac{10}{x} = x + 3
Answer x = 2 or x = −5
20. Factorise 2ac − 3bc − 6bd + 4ad.
Answer (2a − 3b)(c + 2d)
21. (a) Factorise completely 4a − 16a².
Answer 4a(1 − 4a)
(b) Factorise 9b² − c².
Answer (3b − c)(3b + c) -----------------------------------------------------------------------------------------------------------------------------
(c) Factorise x² − 5y − xy + 5x.
Answer (x − 5)(x − y)
22. Express 1 x + 2 + 3 x + 1 \dfrac{1}{x+2} + \dfrac{3}{x+1} as a single fraction in its simplest form.
Answer 4 x + 7 ( x + 1 ) ( x + 2 ) \dfrac{4x + 7}{(x+1)(x+2)}
23. (a) Factorise completely 3 − 12a².
Answer 3(1 − 4a²)
(b) Factorise x² − 6y + 2xy − 3x.
Answer (x − 3)(x + 2y)
24. (a) Factorise completely p²q − pq.
Answer pq(p − 1)
(b) (i) Factorise 5x² + x − 4.
Answer (5x − 4)(x + 1)
(ii) Hence solve 5x² + x − 4 = 0.
Answer x = 4 5 \dfrac{4}{5} 5 4 or x = −1
25. (a) Expand and simplify 10 − 3(3x − 2).
Answer 16 − 9x
(b) Simplify fully
3 x 2 + 16 x + 5 9 x 2 − 1 \dfrac{3x^2 + 16x + 5}{9x^2 - 1} 9 x 2 − 1 3 x 2 + 16 x + 5
Answer 3 x + 1 3 x − 1 \dfrac{3x + 1}{3x - 1} 3 x − 1 3 x + 1
26. (a) Factorise
(i) 4p² − 9q².
Answer (2p − 3q)(2p + 3q)
(ii) 2n² + 5n − 3.
Answer (2n − 1)(n + 3)
(b) Express 3 4 x + 2 3 y \dfrac{3}{4x} + \dfrac{2}{3y} as a single fraction.
Answer 9 y + 8 x 12 x y \dfrac{9y + 8x}{12xy} 12 x y 9 y + 8 x
27. Factorise completely 3xy − 20 + 5x − 12y.
Answer (3x − 12)(y + 1)
28. Simplify fully
4 x 2 − 1 2 x 2 − 9 x − 5 \dfrac{4x^2 - 1}{2x^2 - 9x - 5} 2 x 2 − 9 x − 5 4 x 2 − 1
Answer 2 x + 1 2 x − 5 \dfrac{2x + 1}{2x - 5}
29. Factorise completely
(a) 5 − 20 r 2 5 - 20r^2
Answer 5 ( 1 − 2 r ) ( 1 + 2 r ) 5(1 - 2r)(1 + 2r)
(b) 3 y 2 − 2 x y − 6 x + 9 y 3y^2 - 2xy - 6x + 9y
Answer ( y + 3 ) ( 3 y − 2 x ) (y + 3)(3y - 2x)
30. (a) Given that a = 3 a = 3 a = 3 and b = − 7 b = -7 b = − 7 , evaluate
(i) 2 a − b
Answer 13 13 1
(ii) a 2 + b 2 a^2 + b^2
Answer 58 58
(b) A = 2 r 2 + 5 A = 2r^2 + 5
Rearrange the formula to make r r r the subject.
Answer r = A − 5 2 r = \sqrt{\dfrac{A - 5}{2}}
31. Simplify fully
4 x 2 − 9 2 x 2 − 13 x + 15
Answer 2 x + 3 x − 5 \dfrac{2x + 3}{x - 5}
32. (a) Simplify 8 − 3 ( 2 t + 1 ) 8 - 3(2t + 1)
Answer 5 − 6 t 5 - 6t
(b) Simplify ( 2 x 2 y ) 3 6 x 4 y 4 \dfrac{(2x^2y)^3}{6x^4y^4}
Answer 4 x 2 3 y \dfrac{4x^2}{3y}
33. (a) Factorise 25 a 2 − 5 a 25a^2 - 5a 25 a 2 − 5 a Answer 5 a ( 5 a − 1 ) 5a(5a - 1)
(b) Factorise 9 b 2 − 16 9b^2 - 16
Answer ( 3 b − 4 ) ( 3 b + 4 ) (3b - 4)(3b + 4)
(c) Factorise 4 x y + 3 + 6 y + 2 x 4xy + 3 + 6y + 2x
Answer ( 2 x + 3 ) ( 2 y + 1 ) (2x + 3)(2y + 1)
34. (a) Factorise 9 a 2 − 6 a 9a^2 - 6a Answer 3 a ( 3 a − 2 ) 3a(3a - 2)
(b) Factorise 4 − 25 r 2 4 - 25r^2
Answer ( 2 − 5 r ) ( 2 + 5 r ) (2 - 5r)(2 + 5r)
(c) Factorise 6 c d − x y + 2 c x − 3 d y 6cd - xy + 2cx - 3dy
Answer ( 2 c − y ) ( 3 d + x ) (2c - y)(3d + x)
35. Factorise completely (a) 2 a x − 3 b y + 6 b x − a y 2ax - 3by + 6bx - ay
Answer ( a + 3 b ) ( 2 x − y )
(b) 27 x 2 − 3 y 2 27x^2 - 3y^2
Answer 3 ( 3 x − y ) ( 3 x + y ) 3(3x - y)(3x + y)
36. (a) Factorise 25 r 2 − 4 25r^2 - 4 25 r 2 − 4 Answer ( 5 r − 2 ) ( 5 r + 2 ) (5r - 2)(5r + 2) (b) Factorise
x 2 − 6 x − 3 x y + 18 y x^2 - 6x - 3xy + 18y
Answer ( x − 6 ) ( x − 3 y ) (x - 6)(x - 3y)
37. Express each of the following as a single fraction in its simplest form (a) 2 3 a + 5 2 a \dfrac{2}{3a} + \dfrac{5}{2a}
Answer 19 6 a \dfrac{19}{6a}
(b) 5 2 b 2 + 15 4 b 3 \dfrac{5}{2b^2} + \dfrac{15}{4b^3}
Answer 10 b + 15 4 b 3 \dfrac{10b + 15}{4b^3}
38. (a) Factorise completely 15 a + 3 a b 15a + 3ab Answer 3 a ( 5 + b ) 3a(5 + b)
(b) Factorise 6 k − x y + 2 k r − 3 y
Answer ( 2 k − y ) ( 3 + r ) (2k - y)(3 + r)
39. (a) Simplify 4 c − 3 ( 2 c − 5 ) 4c - 3(2c - 5) Answer 15 − 2 c 15 - 2c
(b) Factorise 8 − 10 y + 12 x − 15 x y
Answer ( 4 − 5 y ) ( 2 + 3 x ) (4 - 5y)(2 + 3x)
40. Factorise (a) 25 x − 5 25x - 5 2
Answer 5 ( 5 x − 1 ) 5(5x - 1)
(b) 2 x 2 − 18 y 2 2x^2 - 18y^2
Answer 2 ( x − 3 y ) ( x + 3 y ) 2(x - 3y)(x + 3y)
41. (a) Expand and simplify ( x − 3 ) 2 (x - 3)^2 Answer x 2 − 6 x + 9 x^2 - 6x + 9 x
(b) Factorise 18 − 6 y + 5 x y − 15 x 18 - 6y + 5xy - 15x
Answer ( 3 − y ) ( 6 − 5 x ) (3 - y)(6 - 5x)
42. (a) Write x 2 − 7 x + 5 x^2 - 7x + 5 x 2 − 7 x + 5 in the form ( x − a ) 2 − b (x - a)^2 - b ( x − a ) 2 − b Answer ( x − 7 2 ) 2 − 29 4 (x - \tfrac{7}{2})^2 - \tfrac{29}{4}
(b) Hence write down the minimum value of x 2 − 7 x + 5 x^2 - 7x + 5
Answer − 29 4 -\dfrac{29}{4}
43. (a) Factorise 1 − 36 p 2 1 - 36p^2 Answer ( 1 − 6 p ) ( 1 + 6 p )
(b) Factorise 4 x + 3 y + x y + 12 4x + 3y + xy + 12
Answer ( x + 3 ) ( y + 4 ) (x + 3)(y + 4)
44. (a) Simplify 7 − 3 ( 5 k − 2 ) Answer 13 − 15 k 13 - 15k
(b) Solve the equation 5 x 2 − 3 x = 0 5x^2 - 3x = 0
Answer x = 0 x = 0 x = 0 or x = 3 5 x = \dfrac{3}{5}
45. Factorise (a) 49 − 9 r 2 49 - 9r^2
Answer ( 7 − 3 r ) ( 7 + 3 r ) (7 - 3r)(7 + 3r)
(b) 15 x y + 5 x − 6 y − 2 15xy + 5x - 6y - 2
Answer ( 3 y + 1 ) ( 5 x − 2 ) (3y + 1)(5x - 2)
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