Which of the following is a factor of (x+y)3−(x3+y3)?
(a) x2+y2+2xy
(b) x2+y2−xy
(c) xy2
(d) 3xy
(x+y)3=x3+y3+3xy(x+y)(x+y)3−(x3+y3)=3xy(x+y)
Hence 3xy is a factor