2x 方减八x 减七等于零解方程
问题描述：
2x 方减八x 减七等于零解方程
答
2x² - 8x -7 = 0
2(x² - 4x +4) -15 = 0
2(x -2)² -15 = 0
(x -2)² = ±15/2
x -2 = ±√30/2
x = 2 ±√30/2