1) x² + 3x + 2 = 0 D = b² - 4ac
D = 9 - 4 * 1 * 2 = 1 x = -b ± √D / 2a , если D > 0
x₁ = -3 + 1 / 2 = -1 x = -b / 2a , если D = 0
x₂ = -3 - 1 / 2 = -2 нет решения, если D < 0
2) 2x² - 7x + 3 = 0
D = 49 - 4 * 2 * 3 = 25
x₁ = 7 + 5 / 4 = 3
x₂ = 7 - 5 / 4 = 0.5
3) x² - 10x + 25 = 0
D = 100 - 4 * 1 * 25 = 0
x = 10 / 2 = 5
4) x² - 9x + 18 = 0
D = 81 - 4 * 1 * 18 = 9
x₁ = 9 + 3 / 2 = 6
x₂ = 9 - 3 / 2 = 3
