用配方法解一元二次方程(1)x2+2x-8=0 (2)x2-4=2x (3)3y2-6y-24=0 (4)4x2-7x+2=0 (5)二分之一x2-2x-9=0
人气：340 ℃ 时间：2020-02-01 09:27:20
解答
（1）x ² + 2 x - 8 = 0x ² + 2 x + 1 = 8 + 1（x + 1）² = 9x + 1 = ± 3x = ± 3 - 1x1 = 3 - 1 = 2x2 = - 3 - 1 = - 4（2）x ² - 4 = 2 xx ² - 2 x - 4 = 0x ² - 2 x + 1 = 4 + 1...
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