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受欢迎的代数 >

completesquare 2x^2+5x-3

解答

配方

2 x^{2} + 5 x - 3

解答

2 (x + \frac{5}{4})^{2} - \frac{49}{8}

求解步骤

2 x^{2} + 5 x - 3

将

2 x^{2} + 5 x - 3

改写为如下形式:

x^{2} + 2 a x + a^{2}

因式分解

2

2 (x^{2} + \frac{5 x}{2} - \frac{3}{2})

2 a = \frac{5}{2} : a = \frac{5}{4}

加和减

(\frac{5}{4})^{2}

2 (x^{2} + \frac{5 x}{2} - \frac{3}{2} + (\frac{5}{4})^{2} - (\frac{5}{4})^{2})

x^{2} + 2 a x + a^{2} = (x + a)^{2}

x^{2} + \frac{5}{2} x + (\frac{5}{4})^{2} = (x + \frac{5}{4})^{2}

2 ((x + \frac{5}{4})^{2} - \frac{3}{2} - (\frac{5}{4})^{2})

化简

2 (x + \frac{5}{4})^{2} - \frac{49}{8}

作图

流行的例子

(x - 1) (x + 2) = e

350000=-2200(t-14)^2+486430

350000 = - 2200 (t - 14)^{2} + 486430

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80 = x^{2}

x^{2} - 9 = 160