Question

x(x减1)减(x的平方减y)等于负2,解2分之x的平方加y的平方减xy

Answer 1

x(x-1)-(x^2-y)=-2

x^2-x-x^2+y=-2

x=y+2

(x/2)^2+y^2-xy

=((y+2)^2/4)+y^2-(y+2)y

=y^2-4y+4