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受欢迎的代数 >

x^2-30x=20

解答

x^{2} - 30 x = 20

解答

x = 15 + 75, x = 15 - 75

+1

十进制

x = 30.65247 \dots, x = - 0.65247 \dots

求解步骤

x^{2} - 30 x = 20

将

20

para o lado esquerdo

x^{2} - 30 x - 20 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 30 ) \pm ( - 30 ) ^{2} - 4 \cdot 1 \cdot ( - 20 )}{2 \cdot 1}

(- 30)^{2} - 4 \cdot 1 \cdot (- 20) = 145

x_{1, 2} = \frac{- ( - 30 ) \pm 14 5}{2 \cdot 1}

将解分隔开

x_{1} = \frac{- ( - 30 ) + 14 5}{2 \cdot 1}, x_{2} = \frac{- ( - 30 ) - 14 5}{2 \cdot 1}

x = \frac{- ( - 30 ) + 14 5}{2 \cdot 1} : 15 + 75

x = \frac{- ( - 30 ) - 14 5}{2 \cdot 1} : 15 - 75

二次方程组的解是:

x = 15 + 75, x = 15 - 75

作图

流行的例子

2 n + 1 = x^{2}

4 x^{2} - 3 x + 17 = 0

solvefor x,x^2y+xy=x^2+x+1

so l v e f or x, x^{2} y + x y = x^{2} + x + 1

12 c^{2} - 24 c + 5 = 0

- y^{2} + 35 y = 306