Question

乘方公式的计算先化简,再求值[2x^2-(x+y)(y-x)][3(-x-y)(y-x)+4y^2]其中x=1/3,y=

Answer 1

[2x^2-(x+y)(y-x)][3(-x-y)(y-x)+4y^2]

=[2x^2+x^2-y^2][-3y^2+3x^2+4y^2]

=(3x^2-y^2)(3x^2+y^2)

=9x^4-y^4

代入数值,得9*（1/3）^4-1=-8/9