a) 2 (x + 1) x+ 2 (x+1)
=(x + 1)(2x + 2)
b) 4x (x-2y) + 8y (2y-x)
=4x (x - 2y) - 8y (x - 2y)
=(4x-8y)(x-2y)
c) (x2 +y) y2- zx2 - zy
=(x2 +y) y2 - z(x2 + y)
=(x2 + y)(y2 - z)
d) 3x (x+1) - 5x2 (x+1) + 7 ( x+1)
=(x + 1)(3x-5x2+7)
e) (2x+1)2 - (x-1)2
=[(2x+1)-(x-1)](2x+1+x-1)
=(2x+1-x+1)(2x+1+x-1)
=(x+2)3x
f) (x+5) 2 - ( x-7)2
=[(x+5) - (x-7)](x+5+x-7)
=(x+5-x+7)(x+5+x-7)
=12(2x-2)