Factorise :
ab(x2+y2)−xy(a2+b2)
Factorise by grouping method:
a2x2+(ax2+1)x+a
x2+y2+x+y+2xy
(i) a2−ab−3a+3b(ii) x2y−xy2+5x−5y(iii) a2−ab(1−b)−b3(iv) xy2+(x−1)y−1(v) (ax+by)2+(bx−ay)2(vi) ab(x2+y2)−xy(a2+b2)(vii) m−1−(m−1)2+am−a