Mathematics
Answer
25(a - 5b)2 - 4(a - 3b)2
= (5(a - 5b))2 - (2(a - 3b))2
Using the formula
[∵ (x2 - y2) = (x + y)(x - y)]
= (5(a - 5b) - 2(a - 3b))((5(a - 5b)) + 2(a - 3b))
= (5a - 25b - 2a + 6b)(5a - 25b + 2a - 6b)
= (5a - 2a - 25b + 6b)(5a + 2a - 25b - 6b)
= (3a - 19b)(7a - 31b)
Hence, 25(a - 5b)2 - 4(a - 3b)2 = (3a - 19b)(7a - 31b)