(y2+2y)2+3(y2+2y)+2
=(y2+2y+2) (y2+2y+1)
= (y2+2y+2) (y+1)2
(x2+3x)2-16
=(x2+3x-4) (x2+3x+4)
=(x+4) (x-1) (x2+3x+4)