a, 8x2y - 8xy + 2x = 2x(4xy – 4y + 1)
b, x2 - 6x – y2 + 9 = (x2 – 6x + 9) – y2
= (x – 9)2 – y2
= (x – 9 - y)(x – 9 + y)
c, (x^2+2x)(x^2+4x+3)-24 = x4 + 2x3 + 4x3 + 8x2 + 3x2 + 6x – 24
= x4 + (2x3 + 4x3) + (4x2 + 3x2) + 6x - 24
= x4 + 6x3 + 7x2 + 6x – 24