计算2x²-5x-1=0

计算2x²-5x-1=0
计算2x²-5x-1=0

计算2x²-5x-1=0
2x²-5x-1=0
2(x²-5/2x)=1
2(x-5/4)²=33/8
(x-5/4)²=33/16
x-5/4=±(√33)/4
x=5/4 ±(√33)/4

四分之（5+根号下33）与四分之（5-根号下33）

判别式=(-5)^2-4*2*(-1)=33
x=(5加减根号33)/4

运用公式法：(-b±∫b^2-4ac)/2a
则x=5±√5²-4×2×（-1）/4
=(5±√33)/4
x1=(5＋√33)/4，x2=(5﹣√33)/4