Question
Factorise:
(3a - 2b)3 + (2b - 5c)3 + (5c - 3a)3

Answer

Put (3a - 2b) = x, (2b - 5c) = y and (5c - 3a) = z.
We have:
x + y + z = 3a - 2b + 2b - 5c + 5c - 3a = 0
Now,
(3a - 2b)3 + (2b - 5c)3 + (5c - 3a)3 = x3 + y3 + z3
= 3xyz [Here, x + y + z = 0. So, x3 + y3 + z3]
= (3a - 2b)(2b - 5c)(5c - 3a)

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