Question

x的4次方加上4y的4次方(因式分解,

Answer 1

x^4+4y^4

=x^4+4y^4+4x^2y^2-4x^2y^2

=(x^2+2y^2)^2-4x^2y^2

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

用添项法!