✔ 最佳答案
1.
x² - 2x - 3 = 0
(x + 1)(x - 3) = 0
x =-1 或 x =3
2.
x² - 5x + 6 = 0
(x - 2)(x - 3) = 0
x =2 或 x =3
3.
x² - 5x - 6 = 0
(x + 1)(x - 6) = 0
x =-1 或 x =6
4.
x² + x - 6 = 0
(x - 2)(x + 3) = 0
x =2 或 x =-3
5.
x² - 4x - 5 = 0
(x + 1)(x - 5) = 0
x =-1 或 x =5
6.
x² + 3x - 10 = 0
(x - 2)(x + 5) = 0
x = 2 或 x =-5
7.
x² - 12x + 10 = 0
x = {-(-12) ± √[(-12)² - 4(1)(10)]} / 2
x = 6 + √26 或 x =6 - √26
(與其他題目要求的解法不一致,可能題目出錯。)
8.
x² - 13x + 40 = 0
(x - 5)(x - 8) = 0
x = 5 或 x =8
9.
x² + 14x + 40 = 0
(x + 4)(x + 10) = 0
x = -4 或 x =-10
10.
x² - 18x - 40 = 0
(x + 2)(x - 20) = 0
x = -2 或 x =20
11.
x² - 5x - 24 = 0
(x + 3)(x - 8) = 0
x = -3 或 x =8
12.
x² + 10x - 56 = 0
(x - 4)(x + 14) = 0
x = 4 或 x =-14
13.
x² - 4x + 4 = 0
(x - 2)² = 0
x = 2 (重根)
14.
x² + 8x + 16 = 0
(x + 4)² = 0
x = -4 (重根)
15.
x² + 6x - 16 = 0
(x - 2)(x + 8) = 0
x = 2 或 x =-8
16.
x² + 6x + 8 = 0
(x + 2)(x + 4) = 0
x = -2 或 x =-4