先化简再求值（x²-xy）-3（2x²-3xy）-2[x²-（2x²-xy+y²）] 其中x=1,y=3

原式
=(x^2-xy)-6x^2+9xy-2x^2+2(2x^2-xy+y^2)
=x^2-xy-6x^2+9xy-2x^2+4x^2-2xy+2y^2
=x^2-6x^2-2x^2+4x^2+9xy-2xy-xy+2y^2
=-3x^2+6xy+2y^2
=-3*1+6*1*3+2*3^2
=-3+18+18
=33