Question

Factorise by using formula: $(5a-3b{)}^2-16b^2$

• A. $(5a+b)(5-7b)$
• B. $(5a+b)(5a-7)$
• C. $(5a+b)(5a-7b)$
• D. $(5+b)(5a-7b)$

Answer 1

The correct option is C $(5a+b)(5a-7b)$

$Factorizing{(5a-3b)}^2-\left\{4\right(b){\}}^2,=(5a-3b+4b\left)\right(5a-3b-4b)=(5a+b\left)\right(5a-7b)$

using the identity $(a^2-b^2)=(a+b)(a-b)$