Q3 of 20 Page 228

Factorize: 8a3 – b3 – 12a2b + 6ab2.

To factorize 8a3 – b3 – 12a2b + 6ab2, we make use of the identity: (x – y)3 = x3 – 3x2y + 3xy2 – y3


This expression 8a3 – b3 – 12a2b + 6ab2 has four terms and is similar to the right hand side of the above identity.


Observe 8a3=(2a)3, 12a2b=3(2a)2(b) and 6ab2=3(2a)(b)2


8a3 – b3 – 12a2b + 6ab2 = (2a)3 – 3(2a)2(b) + 3(2a)(b)2 – b3


8a3 – b3 – 12a2b + 6ab2 = (2a – b)3


Hence, the factorization of8a3 – b3 – 12a2b + 6ab2 is (2a – b)3.


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