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受欢迎的代数 >

completesquare 2x^2+7x-15=0

解答

2 x^{2} + 7 x - 15 = 0

解答

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

+1

十进制

x = 1.5, x = - 5

求解步骤

2 x^{2} + 7 x - 15 = 0

将

15

到右边

2 x^{2} + 7 x = 15

两边除以

2

\frac{2 x ^{2} + 7 x}{2} = \frac{15}{2}

x^{2} + \frac{7 x}{2} = \frac{15}{2}

改写为形式

(x + a)^{2} = b

(x + \frac{7}{4})^{2} = \frac{169}{16}

若

f^{2} (x) = a

，解为

f (x) = a, - a

解

x + \frac{7}{4} = \frac{169}{16} : x = \frac{3}{2}

解

x + \frac{7}{4} = - \frac{169}{16} : x = - 5

二次方程组的解是:

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

作图

流行的例子

2 (x^{2} - 1) = x^{2} + 7

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

2 x^{2} + 7 x + 12 = 0

(x) = x^{2} - 1

p^{2} - 8 p + 12 = 0