Question

Factorise:
4x4+ 25y4+ 19x2y2

Answer 1

4x4+ 25y4+ 19x2y2
= 4x4 + 25y4 + 20x2y2 - x2y2
= (2x2)2 + (5y2)2 + 2 x (2x2) x (5y2) - x2y2
= [(2x2)2 + (5y2) + 2 x (2x2) x (5y2)] -x2y2
= [2x2 + 5y2] - (xy)2
= (2x2 + 5y2 - xy)(2x2 - 5y + xy).