先化简在求值,已知x=2,y=3,求代数式(x+y)三方-xy(x+y)
问题描述:
先化简在求值,已知x=2,y=3,求代数式(x+y)三方-xy(x+y)
答
(x+y)三方-xy(x+y)
=x^3+3x^2y+3xy^2+y^3 -x^2y-xy^2
=x^3+2x^2y+2xy^2+y^3
=2^3+2×2^2×3+2×2×3^2+3^3
=8+24+36+27
=95