Factorize:
a2 + 6a – 91
Now, first we have to find out the numbers whose-
Sum = 6 and
Product = - 91
The numbers are 13 and 7,
So,
= a2 + 13a – 7a – 91
= a(a + 13) – 7(a + 13)
= (a + 13) (a – 7)