Question

a square + 23 a b + 42 B square

Answer 1

a^2+23ab+42b^2
a^2+21ab+2ab+42b^2
a(a+21b)+2b(a+21b)
(a+21b)(a+2b)

Answer 2

a²+23ab+42b

=a²+2ab+21ab+42b²

=a(a+2b) +21b(a+2b)

=(a+2b) (a+21b)