6x-1=2 x=1/2 y^2-y=2 y=-1或y=2
(5x^2y+5xy-7x)-(4x^2+5xy-7x)
=5x^2y-4x^2
=x^2(5y-4)
y=-1 x^2(5y-4)=1/4*(-9)=-9/4
y=2 x^2(5y-4)=1/4*6=3/2