解方程2x²-6x-6=0

解方程2x²-6x-6=0
解方程2x²-6x-6=0

解方程2x²-6x-6=0
2x²-6x-6=0
两边除以2,得
x²-3x-3=0
∵a=1,b=-3,c=-3
Δ=(-3)²－4×1×(-3)
=9＋12
=21
∴x=½(3±√21)
x1=½(3+√21),x2=½(3-√21)

韦达定理

x=【6±根号84】/4
=【3±根号21】/2

2x²-6x-6=0
4x^2-12x+9-9-12=0
(2x-3)^2-21=0
(2x-3-√21）(2x-3+√21）=0
x1=(3+√21)/2
x2=(3-√21)/2