Question

Factorise the following by grouping the terms:
xy(a² + 1) + a(x² + y²)

Answer 1

xy(a² + 1) + a(x² + y²)
= a²xy + xy + ax² + ay²
= (a²xy + ax²) + (ay² + xy)
= ax(ay + x) + y(ay + x)
= (ay + x)(ax + y).