The Total solution for NCERT class 6-12
(a + b)3 – 8(a – b)3= (a + b)2 – (2a – 2b)3= (a+ b – 2a + 2b) [(a + b)2 + (a + b) (2a-2b) + (2a –2b)2)]= (3b – a) [a2 + b2 + 2ab + 2a2 – 2ab+ 2ab – 2b2 + 4a2 – 8ab + 4b2]= (3b – a) [7a2 – 6ab + 3b2]