帮我做做下面几道题,
问题描述：
帮我做做下面几道题,
a-a^3
x^3-xy^3
4x^3y^3-9xy
4x^2-8x-12y-9y^2
已知a^2+b^2=5c^2+d^2=2求代数值（ac+bd）^2+(ad-bc)^2
答
a-a^3=a(1-a^2)=a(1+a)(1-a)x^3y-xy^3=x(x^2-y^2)=x(x+y)(x-y)4x^3y^3-9xy=xy(4x^2y^2-9)=xy(2xy+3)(2xy-3)4x^2-8x-12y-9y^2=4x^2-8x+4-(9y^2+12y+4)=4(x-1)^2-(3y+2)^2=(2x-2+3y+2)(2x-2-3y-2)=(2x+3y)(2x-3y-4)