Question

Factorise the following polynomials.
(a) 14(3y – 5z)3 + 7(3y – 5z)2
(b) 5m-2mp-6p+15
(c) m2 – 10m – 56
(d) 4x2 + 9 – 12x – a2 – b2 + 2ab

Answer 1

Answer:

a) 14(3y – 5z)3 + 7(3y – 5z)2

= 7(3y – 5z)2 [2(3y – 5z) +1]

= 7(3y – 5z)2 (6y – 10z + 1)

c) m2 – 10m – 56

= m2 – 14m + 4m – 56

[14 – 4 = 10; 4 × 4 = 56]

= m(m – 14) + 6(m – 14)

= (m – 14) (m + 6).

d) 4x2 + 9 – 12x – a2 – b2 + 2ab

= (4x2 – 12x + 9) – (a2 + b2 – 2ab)

= (2x – 3)2 – (a – b)2

= [(2x – 3) + (a – b)] [(2x – 3) – (a – b)]

= (2x – 3 + a – b)(2x – 3 – a + b)

sorry, I don't know the answer of (b).