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受欢迎的代数 >

x^2=x+72

解答

x^{2} = x + 72

解答

x = 9, x = - 8

求解步骤

x^{2} = x + 72

将

72

para o lado esquerdo

x^{2} - 72 = x

将

x

para o lado esquerdo

x^{2} - 72 - x = 0

改写成标准形式

a x^{2} + b x + c = 0

x^{2} - x - 72 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 1 ) \pm ( - 1 ) ^{2} - 4 \cdot 1 \cdot ( - 72 )}{2 \cdot 1}

(- 1)^{2} - 4 \cdot 1 \cdot (- 72) = 17

x_{1, 2} = \frac{- ( - 1 ) \pm 17}{2 \cdot 1}

将解分隔开

x_{1} = \frac{- ( - 1 ) + 17}{2 \cdot 1}, x_{2} = \frac{- ( - 1 ) - 17}{2 \cdot 1}

x = \frac{- ( - 1 ) + 17}{2 \cdot 1} : 9

x = \frac{- ( - 1 ) - 17}{2 \cdot 1} : - 8

二次方程组的解是:

x = 9, x = - 8

作图

流行的例子

(2k+2)x^2-4x+k=0

(2 k + 2) x^{2} - 4 x + k = 0

60x^2+4.75x-58.8=0

60 x^{2} + 4.75 x - 58.8 = 0

2 x^{2} + 14 x + 17 = 0

12 x (3 x - 2) = 0

solvefor x,4x^2-9y^2-z^2=0

so l v e f or x, 4 x^{2} - 9 y^{2} - z^{2} = 0