x(3x-2y)+(2x+y)²+(2x-y)(x+y)-3(xy+10)=3x^2-2xy+4x^2+4xy+y^2+2x^2+xy-y^2-3xy-30=9x^2-30 x=-2,=36-30=6
原式=3x(2)-2xy+4x(2)+y(2)+4xy+2x(2)+2xy-xy-y(2)-3xy-30=9x(2)-30=36-30=6
