Question

Factorise:
(vi) 64(a - b)2 - 81(a + b)2​

Answer 1

hope this helps u

64(a + b)² - 81(a - b)²

= [8(a + b)]² - [ 9(a - b)]²

=> (8a + 8b)² - (9a - 9b)²  

Now, using the identity,  

a² - b² = (a + b)(a - b), we can solve.

=> (8a + 8b)² - (9a - 9b)²

=> [8a + 8b - (9a - 9b)](8a + 8b + 9a - 9b)  

=> (8a + 8b - 9a + 9b)(17a - b)

=> (17b - a)(17a - b)

Your answer :- (17b - a)(17a - b)