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受欢迎的代数 >

2(y^2+3y)=9

解答

2 (y^{2} + 3 y) = 9

解答

y = \frac{3 ( 3 - 1 )}{2}, y = - \frac{3 ( 1 + 3 )}{2}

+1

十进制

y = 1.09807 \dots, y = - 4.09807 \dots

求解步骤

2 (y^{2} + 3 y) = 9

展开

2 (y^{2} + 3 y) : 2 y^{2} + 6 y

2 y^{2} + 6 y = 9

将

9

para o lado esquerdo

2 y^{2} + 6 y - 9 = 0

使用求根公式求解

y_{1, 2} = \frac{- 6 \pm 6 ^{2} - 4 \cdot 2 ( - 9 )}{2 \cdot 2}

6^{2} - 4 \cdot 2 (- 9) = 63

y_{1, 2} = \frac{- 6 \pm 6 3}{2 \cdot 2}

将解分隔开

y_{1} = \frac{- 6 + 6 3}{2 \cdot 2}, y_{2} = \frac{- 6 - 6 3}{2 \cdot 2}

y = \frac{- 6 + 6 3}{2 \cdot 2} : \frac{3 ( 3 - 1 )}{2}

y = \frac{- 6 - 6 3}{2 \cdot 2} : - \frac{3 ( 1 + 3 )}{2}

二次方程组的解是:

y = \frac{3 ( 3 - 1 )}{2}, y = - \frac{3 ( 1 + 3 )}{2}

作图

流行的例子

3x^2-110x+900=0

3 x^{2} - 110 x + 900 = 0

(x + 4)^{2} = - 36

x^{2} + (b + 4) x = 0

completesquare x^2+4x=5

co m pl e t es q u a re x^{2} + 4 x = 5

2 x^{2} + 7 = 31