Question

Factorise a2 + 7a – 120

Answer 1

Answer:

(a-8)(a+15)

Step-by-step explanation:

Question

Factorize a²+7a-120

Understanding

Here algebraic identity i.e. (x+a)(x+b)=x²+(a+b)x+a×b.

Solution

a²+7a-120

=a²+(15-8)a-120

(As 15 is considered as a and 8 is considered as b. When 15 and -8 are multiplied to each other it becomes -120 and when added it becomes 7. So we have taken it as 15 and -8.)

=a²+15a-8a-120

=a(a+15)-8(a+15)

(Here we have taken 'a' as common in (a+15) and '-8' as common of (a+15))

=(a-8)(a+15)

(Now we have taken (a+15) as common.)