Question

1. Factorise:
a)3x + 18
b) 15xy + 15 + 9x + 25 y
c) 45xy + 15 x
d) x2 + 8x + 16
e) x2 – 16
f) x4 – 121
g) x2 + 9x + 20
h) y2 – 7y + 12

Answer 1

1. 3x+18= 3(x+6)

2. 9x + 15xy + 25 y +15

= 3x(3+5y) + 5(5y+3)

= (3x+5)(3+5y)

3. 15x+45xy = 15x(1+3y)

4. x² +8x+16

= x² + 4x +4x +16

= x(x+4) + 4(x +4)

= (x+4)(x+4)

= (x+4)²

5. x² - 16

= (x-4)(x+4)

6. x⁴-121

= (x²+11)(x²-11)

7.x²+9x+20

= x²+5x+4x+20

= x(x+5)+4(x+5)

= (x+4)(x+5)

8. y²-7y+12

= y²-4x-3y+12

= y(y-4) -3(y-4)

= (y-4)(y-3)