x²=2x+1,用公式法解这道方程
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x²=2x+1,用公式法解这道方程
x²=2x+1,
用公式法解这道方程
x²=2x+1,用公式法解这道方程
x ² = 2 x + 1
x ² - 2 x - 1 = 0
a = 1 .b = - 2 ,c = - 1
△ = b ² - 4 a c
= (- 2)² - 4 × 1 × (- 1)
= 4 + 4 = 8 > 0
∴ x = 【±√△ - b】/ 2 a
= (±√8 - (- 2))/ 2 × 1
= (±2√2 + 2)/ 2
x1 = √2 + 1
x2 = 1 - √2
x=2(+-)根号(4-(-4))/2=(+-)根号2+1.
x²=2x+1
得x²-2x+1=2
(x-1)²=2
x-1=±√2
∴ x1 = √2 + 1
x2 = 1 - √2