Question

(3a-7b)square
+84ab = (3a+76)square

Answer 1

Answer :

=(3a)

2

+2(3a)(7b)+(7b)

2

=9a

2

+42ab+14b

2

Answer 2

Answer:

(3a-7b)^2+84ab=(3a+7b)^2

84ab=(3a+7b)^2-(3a-7b)^2

={(3a+7b)+(3a-7b)}{(3a+7b)-(3a-7b)}

=(3a+7b+3a-7b)(3a+7b-3a+7b)

=6a.14b

=84ab (proved)