Question

6a³+3a²-3a
factorise it
​

Answer 1

Answer:

Write

a

3

−3a

2

+3a+7=a

3

−3a

2

+3a−1+8=(a−1)

3

+8

But

(a−1)

3

+8=(a−1)

3

+2

3

=(a−1+2)[(a−1)

2

−2(a−1)+4]

Simplification gives

[(a−1)

2

−2(a−1)+4]=a

2

−2a+2−2a+1+4=a

2

−4a+7

Thus we obtain

a

3

−3a

2

+3a+7=(a+1)(a

2

−4a+7).