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受欢迎的代数 >

(n(n-3))/2 =27

解答

\frac{n ( n - 3 )}{2} = 27

解答

n = 9, n = - 6

求解步骤

\frac{n ( n - 3 )}{2} = 27

在两边乘以

2

n (n - 3) = 54

展开

n (n - 3) : n^{2} - 3 n

n^{2} - 3 n = 54

将

54

para o lado esquerdo

n^{2} - 3 n - 54 = 0

使用求根公式求解

n_{1, 2} = \frac{- ( - 3 ) \pm ( - 3 ) ^{2} - 4 \cdot 1 \cdot ( - 54 )}{2 \cdot 1}

(- 3)^{2} - 4 \cdot 1 \cdot (- 54) = 15

n_{1, 2} = \frac{- ( - 3 ) \pm 15}{2 \cdot 1}

将解分隔开

n_{1} = \frac{- ( - 3 ) + 15}{2 \cdot 1}, n_{2} = \frac{- ( - 3 ) - 15}{2 \cdot 1}

n = \frac{- ( - 3 ) + 15}{2 \cdot 1} : 9

n = \frac{- ( - 3 ) - 15}{2 \cdot 1} : - 6

二次方程组的解是:

n = 9, n = - 6

作图

流行的例子

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