Factorise
(i) 7a3 + 7a – 2a2 – 2
(ii) 4ax + 3by – 3ay –4bx
(iii) x3 + y3 + x2y + xy2
(i) 7a3 + 7a – 2a2 – 2 = 7a(a2 + 1) – 2(a2 + 1)
= (a2 + 1)(7a – 2)
(ii) The terms of 4ax + 3by – 3ay – 4bx can be rearranged and factorized.
4ax – 4bx – 3ay + 3by = 4x(a – b) - 3y(a - b)
= (a – b)(4x – 3y)
(iii) x3 + y3 + x2y + xy2 = x3 + x2y + xy2 + y3
= x2(x + y) + y2 (x + y)
= (x + y) (x2 + y2)