9x^4-24x^2y^2+16y^2
=9x^4-9x^2y^2+16y^2-16x^2y^2
==9(x^4-x^2y^2)+16(y^2-x^2y^2)
=9(x^2+xy)(x^2-xy)+16(y-xy)(x+xy)
=9x^2(x+y)(x-y)+16y^2(1-x)(1+x)
因式分解9x的4次方-24x的平方y的平方+16y的平方
9x^4-24x^2y^2+16y^2
=9x^4-9x^2y^2+16y^2-16x^2y^2
==9(x^4-x^2y^2)+16(y^2-x^2y^2)
=9(x^2+xy)(x^2-xy)+16(y-xy)(x+xy)
=9x^2(x+y)(x-y)+16y^2(1-x)(1+x)