Cambridge International Mathematics

EXERCISE 21B.2

1 Solve forx:

a x^2 ¡ 7 x=0 b x^2 ¡ 5 x=0 c x^2 =8x

d x^2 =4x e 3 x^2 +6x=0 f 2 x^2 +5x=0

g 4 x^2 ¡ 3 x=0 h 4 x^2 =5x i 3 x^2 =9x

2 Solve forx:

a x^2 ¡1=0 b x^2 ¡9=0 c (x¡5)^2 =0

d (x+2)^2 =0 e x^2 +3x+2=0 f x^2 ¡ 3 x+2=0

g x^2 +5x+6=0 h x^2 ¡ 5 x+6=0 i x^2 +7x+6=0

j x^2 +9x+14=0 k x^2 +11x=¡ 30 l x^2 +2x=15

m x^2 +4x=12 n x^2 =11x¡ 24 o x^2 =14x¡ 49

3 Solve forx:

a x^2 +9x+20=0 b x^2 +11x+28=0 c x^2 +2x=8

d x^2 +x=12 e x^2 +6=5x f x^2 +4=4x

g x^2 =x+6 h x^2 =7x+60 i x^2 =3x+70

j 10 ¡ 3 x=x^2 k x^2 +12=7x l 9 x+36=x^2

4 Solve forx:

a 2 x^2 +2=5x b 3 x^2 +8x=3 c 3 x^2 +17x+20=0

d 2 x^2 +5x=3 e 2 x^2 +5=11x f 2 x^2 +7x+5=0

g 3 x^2 +13x+4=0 h 5 x^2 =13x+6 i 2 x^2 +17x=9

j 2 x^2 +3x=5 k 3 x^2 +2x=8 l 2 x^2 +9x=18

5 Solve forx:

a 6 x^2 +13x=5 b 6 x^2 =x+2 c 6 x^2 +5x+1=0

d 21 x^2 =62x+3 e 10 x^2 +x=2 f 10 x^2 =7x+3

6 Solve forxby first expanding brackets and then making one side of the equation zero:

a x(x+5)+2(x+6)=0 b x(1 +x)+x=3 c (x¡1)(x+9)=8x

d 3 x(x+2)¡5(x¡3) = 17 e 4 x(x+1)=¡ 1 f 2 x(x¡6) =x¡ 20

7 Solve forxby first eliminating the algebraic fractions:

a

x

3

=

2

x

b

4

x

=

x

2

c

x

5

=

2

x

d

x¡ 1

4

=

3

x

e

x¡ 1

x

=

x+11

5

f

x

x+2

=

1

x

g

2 x

3 x+1

=

1

x+2

h

2 x+1

x

=3x i

x+2

x¡ 1

=

x

2

8 Solve forx:

a

6

x+1

+

4

x

=4 b

3

x

+

5

x¡ 2

=¡ 2 c

1

x

¡

5

x+2

=¡ 6 d

3

x¡ 2

¡

4

x

=¡ 7

9 Solve forx:

a x^4 ¡ 5 x^2 +4=0 b x^4 ¡ 7 x^2 +12=0 c x^4 =4x^2 +5

Hint: Treat them as quadratics in the variablex^2.

426 Quadratic equations and functions (Chapter 21)

IGCSE01

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Y:\HAESE\IGCSE01\IG01_21\426IGCSE01_21.CDR Monday, 27 October 2008 2:09:04 PM PETER