(2x+y)^2-(2x-y)^2+x(-2y+x)=4x^2+4xy+y^2-(4x^2-4xy+y^2)+(-2xy+x^2)=4x^2+4xy+y^2-4x^2+4xy-y^2)-2xy+x^2=6xy+x^2其中x=3 y=1/2,代入上式则原式=6xy+x^2=6*3*1/2+3^2=9+9=18 祝您生活愉快~
=4xy+4xy+x^2-2xy=x^2+6xy=9+9=18
