2x²+3x-7=0
x²+3x/2=7/2
x²+3x/2+(3/4)²=7/2+9/16=56/16+9/16=65/16
(x+3/4)²=65/16
x+3/4=±√65/4
x1=(√65-3)/4
x2=(-√65-3)/4