x²-3x-10=0
x=[3±√(9+40)]/2
x1=5,x2=-2
2x²-3x+1=2(x²-3x/2)+1=2(x-3/4)²-1/8=0
就是 (x-3/4)²=1/16
x-3/4=±1/4
x1=1,x2=1/2