2x-y-(2y平方-x平方)-5x+y+(x平方+2y平方),x=-1,y=1

问题描述:

2x-y-(2y平方-x平方)-5x+y+(x平方+2y平方),x=-1,y=1

2x-y-(2y^2-x^2)-5x+y+(x^2+2y^2)
=2x-y-2y^2+x^2-5x+y+x^2+2y^2
=2x^2-3x
=2+3
=5