Select a suitable identity and find the following products(3t + 9s) (3t – 9s)

Question

Philoid · Accepted Answer

Given:(3t + 9s) (3t – 9s),it is a product of 2 binomial expressions which have the terms :(3t + 9s) and (3t – 9s).

Now when we compare these expressions with the identities, we

find it in the form of (a-b)(a + b),where a = 3t and b = 9s,

The identity (a-b)(a + b) = a²-b²,

Hence, (3t + 9s) (3t – 9s) = (3t)²-(9s)² = 9t²-81s²

Select a suitable identity and find the following products
(3t + 9s) (3t – 9s)