Question

分解因式-xy(1-xy)-x^3y^3

Answer 1

-xy(1-xy)-x^3y^3

=-xy(1-xy+x^2+y^2)

修改：

1-xy(1-xy)-x^3y^3

=1-xy+x^2y^2-x^3y^3

=1-xy+x^2y^2(1-xy)

=(1-xy)(x^2+y^2+1)