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受欢迎的代数 >

x(3x+1)=x^2+15

解答

x (3 x + 1) = x^{2} + 15

解答

x = \frac{5}{2}, x = - 3

+1

十进制

x = 2.5, x = - 3

求解步骤

x (3 x + 1) = x^{2} + 15

展开

x (3 x + 1) : 3 x^{2} + x

3 x^{2} + x = x^{2} + 15

将

15

para o lado esquerdo

3 x^{2} + x - 15 = x^{2}

将

x^{2}

para o lado esquerdo

2 x^{2} + x - 15 = 0

使用求根公式求解

x_{1, 2} = \frac{- 1 \pm 1 ^{2} - 4 \cdot 2 ( - 15 )}{2 \cdot 2}

1^{2} - 4 \cdot 2 (- 15) = 11

x_{1, 2} = \frac{- 1 \pm 11}{2 \cdot 2}

将解分隔开

x_{1} = \frac{- 1 + 11}{2 \cdot 2}, x_{2} = \frac{- 1 - 11}{2 \cdot 2}

x = \frac{- 1 + 11}{2 \cdot 2} : \frac{5}{2}

x = \frac{- 1 - 11}{2 \cdot 2} : - 3

二次方程组的解是:

x = \frac{5}{2}, x = - 3

作图

流行的例子

(4 x + 9) (5 x - 7) = 0

0 = 3 (x - 2)^{2}

4 x^{2} = 31 x + 8

x^{2} - 1 x - 12 = 0

solvefor x,2=3x^2-4y^3

so l v e f or x, 2 = 3 x^{2} - 4 y^{3}