Question

ВАРИАНТ 9 1) 15х2 + 4 = 16х 2) 7х2 = 4х – 3 3) 2х – 5х2 = 0 4) 5х2 – 20 = 0 5) 7х + 3 + 4х2 = 0 6) х2 – 9х + 18 = 0 7) 16k2 + 9 – 24k = 0

Answer 1

1)
15x² - 16x + 4 = 0
D = 256 - 240 = 16
x₁ = (16+4)/30 = 2/3
x₂ = (16-4)/30 = 0,4

2)
7x²- 4x + 3 = 0
D = 16 - 84 < 0
не имеет решений в действительных числах

3)
x(2 - 5x) = 0
x₁ = 0
x₂ = 0,4

4)
5x² - 20 = 0
x² = 4
x₁ = -2
x₂ = 2

5)
4x² + 7x + 3 = 0
D = 49 - 48 = 1
x₁ = (-7-1)/8 = -1
x₂ = (-7+1)/8 = -6/8 = -3/4 = -0,75

6)
x² - 9x + 18 = 0
D = 81 - 72 = 9
x₁ = (9-3)/2 = 3
x₂ = (9+3)/2 = 6

7)
16k² - 24k + 9 = 0
(4k - 3)² = 0
x = 3/4 = 0,75