(1)x^2-3x+1=0
x=（3+√5）/2 x==（3-√5）/2
(2)2x^2+6=7x
x=2 x=3/2
(3)3x^2-9x+2=0
x=（9+√57）/6 x=（9-√57）/6
(4)2x^2+3x-2=0
x=-2 x=1/2