Question

(1-x^2)(1-y^2)-4xy factorise

Answer 1

(1-x²) (1 - y²) + 4xy

1- x² - y² + x²y² + 4xy

(1 + 2xy + x²y²) — (y² + x² − 2xy)

(1 + xy)²(x - y)²

(1 + xy + x - y)(1+xy − x+y)