Х² + 3х = 0
х (х + 3) = 0
Х1 = 0
Х2 = - 3/1 = -3
4х² + 28х + 49 = 0
D = 28² - 4 × 4 × 49 = 784 - 784 = 0
D = 0, будет один корень
Х = - 28/2*4 = - 28/8 = - 3,5
9х² + 6 = 21х
9х² - 21х +6 =0
D = (-21)² - 4 * 9 * 6 = 441 - 216 = 225
Х1 = - (-21) - √225 21 - 15
------------------- = ------------ = 1/3
2 * 9 18
Х2 = -(-21) + √225 21 + 15
----------------------- = -------------------- = 36/18 = 2
2 * 9 18
3х² - 8 +10х = 0
3х² + 10х - 8 =0
D = 10² - 4 * 3 * (-8) = 100 + 96 = 196
Х1 = -10 - √196 - 10 - 14
------------------ = -------------- = - 24/6 = - 4
2 * 3 6
Х2 = - 10 + √196 - 10 + 14
--------------- = -------------- = 2/3
2 * 3 6
14 + 5х² - 10х = 0
5х² - 10х + 14 = 0
D + (-10)² - 4 * 5 * 14 = 100 - 280 = - 180
D < 0 корней нет
5х - х² = 0
-х² + 5х = 0
х² - 5х = 0
Х1 = 0
Х2 = - (-5/1) = 5
169 - b² = 0
- b² + 169 = 0
b² - 169 = 0
(b - √169/1) (b + √169/1) = Х1,2 = + - 14