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受欢迎的代数 >

(n+3(n))/2 =(n(n-3))/2+15

解答

\frac{n + 3 ( n )}{2} = \frac{n ( n - 3 )}{2} + 15

解答

n = \frac{7}{2} + i \frac{71}{2}, n = \frac{7}{2} - i \frac{71}{2}

求解步骤

\frac{n + 3 ( n )}{2} = \frac{n ( n - 3 )}{2} + 15

在两边乘以

2

4 n = n (n - 3) + 30

展开

n (n - 3) + 30 : n^{2} - 3 n + 30

4 n = n^{2} - 3 n + 30

交换两边

n^{2} - 3 n + 30 = 4 n

将

4 n

para o lado esquerdo

n^{2} - 7 n + 30 = 0

使用求根公式求解

n_{1, 2} = \frac{- ( - 7 ) \pm ( - 7 ) ^{2} - 4 \cdot 1 \cdot 30}{2 \cdot 1}

化简

(- 7)^{2} - 4 \cdot 1 \cdot 30 : 71 i

n_{1, 2} = \frac{- ( - 7 ) \pm 71 i}{2 \cdot 1}

将解分隔开

n_{1} = \frac{- ( - 7 ) + 71 i}{2 \cdot 1}, n_{2} = \frac{- ( - 7 ) - 71 i}{2 \cdot 1}

n = \frac{- ( - 7 ) + 71 i}{2 \cdot 1} : \frac{7}{2} + i \frac{71}{2}

n = \frac{- ( - 7 ) - 71 i}{2 \cdot 1} : \frac{7}{2} - i \frac{71}{2}

二次方程组的解是:

n = \frac{7}{2} + i \frac{71}{2}, n = \frac{7}{2} - i \frac{71}{2}

作图

流行的例子

28 x^{2} + 14 x + 1 = 0

因式分解 6x^2+4x+1=9x

f a c t or 6 x^{2} + 4 x + 1 = 9 x

a^{2} + 3 6^{2} = 3 9^{2}

x^{2} + 10 x + 25 = 14

solvefor t,r(t)=4t-3t^2+5

so l v e f or t, r (t) = 4 t - 3 t^{2} + 5