2yx-2y^2+7y^2-3xy
3x^2-24x-6x^2-12x
8x^2-16x-18x^2+12x=-10x^2-4x=-2x(5x+2)
-2*8(5*8+2)=-16*42=-672
15y^2-10y-14y^2+7y=y^2-3y=y(y-3)
6(6-3)=6*3=18
x^2-3x+1=x^2+2
x^2-3x+1-x^2-2=0
-3x-1=0
3x+1=0
3x=-1
x=-1/3
3t-t^2=2t-t
3t-t^2-2t+t=0
-t^2+2t=0
t^2-2t=0
t(t-2)=0
t=0 t=2

2x+31=0
2x=-31
x=-15.5