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受欢迎的代数 >

solvefor n,x=(n(n+1))/2

解答

求解

n, x = \frac{n ( n + 1 )}{2}

解答

n = \frac{- 1 + 1 + 8 x}{2}, n = \frac{- 1 - 1 + 8 x}{2}

求解步骤

x = \frac{n ( n + 1 )}{2}

在两边乘以

2

2 x = n (n + 1)

展开

n (n + 1) : n^{2} + n

2 x = n^{2} + n

交换两边

n^{2} + n = 2 x

将

2 x

para o lado esquerdo

n^{2} + n - 2 x = 0

使用求根公式求解

n_{1, 2} = \frac{- 1 \pm 1 ^{2} - 4 \cdot 1 \cdot ( - 2 x )}{2 \cdot 1}

化简

1^{2} - 4 \cdot 1 \cdot (- 2 x) : 1 + 8 x

n_{1, 2} = \frac{- 1 \pm 1 + 8 x}{2 \cdot 1}

将解分隔开

n_{1} = \frac{- 1 + 1 + 8 x}{2 \cdot 1}, n_{2} = \frac{- 1 - 1 + 8 x}{2 \cdot 1}

n = \frac{- 1 + 1 + 8 x}{2 \cdot 1} : \frac{- 1 + 1 + 8 x}{2}

n = \frac{- 1 - 1 + 8 x}{2 \cdot 1} : \frac{- 1 - 1 + 8 x}{2}

二次方程组的解是:

n = \frac{- 1 + 1 + 8 x}{2}, n = \frac{- 1 - 1 + 8 x}{2}

作图

流行的例子

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4.905 t^{2} - 25.11 t + 11 = 0

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3 + x (x - 2) = 6 (x - 2)

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