2X^2-4X-5=0 求解此方程,

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2X^2-4X-5=0 求解此方程,

2X^2-4X-5=0 求解此方程,
2X^2-4X-5=0 求解此方程,

2X^2-4X-5=0 求解此方程,
2X^2-4X-5=0
2(x^2-2x)=5
2(x^2-2x+1-1)=5
2(x-1)^2=7
(x-1)^2=7/2
x-1=±√(7/2)
x=1± √14/2

2x²-4x=5
x²-2x=5/2
x²-2x+1=7/2
(x-1)²=14/4
∴x=1+√14/2 x=1-√14/2

2x²-4x-5=0
2x²-4x+2-7=0
2(x²-2x+1)=7
2(x-1)²=7
(x-1)²=7/2
x=1±√(7/2)