2y²+8y+7＝0
2y²+8y+8＝1
2(y+2)^2=1
y+2=±√2/2
y=-2±√2/2
-1/2x²-3x=1
x²+6x=-2
x²+6x+9=-2+9
(x+3)^2=7
x+3=±√7
x=-3±√7