Factorize the following expression : \((a + b)^3 – 8(a – b)^3\)

\[ (a + b)^3 – 8(a – b)^3 \] \[ = (a + b)^3 – [2(a – b)]^3 \] \[ = \left[(a + b) – 2(a – b)\right] \left[(a + b)^2 + 2(a + b)(a – b) + 4(a – b)^2\right] \] \[ = (-a + 3b) \left[(a + b)^2 + 2(a + b)(a – b) + 4(a – b)^2\right] \] \[ = (3b – a)(7a^2 – 6ab + 3b^2) \]