4.
a) (х + 2)² - 3 = 0
х² + 4х + 4 - 3 = 0
х² + 4х - 1 = 0
D = 4² - 4 • (-1) = 16 + 4 = √20 = 2√5
x1 = -4 - 2√5 / 2 = -2 - √5
x2 = -4 + 2√5 / 2 = -2 + √5
б) 9x² - 6x - 1 = 0
D = 6² - 4 • (-1) • 9 = √72 = 3√8
x1 = 6 - 3√8 / 18 = 2 - √8 / 6 = 1 - √8 / 3
x2 = 6 + 3√8 / 18 = 2 + √8 / 6 = 1 + √8 / 3
5.
а) -2(х - 3)² + 4 = 0
-2(х² - 6х + 9) + 4 = 0
-2х² + 12х - 18 + 4 = 0
-2х² + 12х - 14 = 0
2х² - 12х + 14 = 0
х² - 6х + 7 = 0
D = 6² - 4 • 7 = √8 = 2√2
x1 = 6 - 2√2 / 2 = 3 - √2
x2 = 6 + 2√2 / 2 = 3 + √2
б) -х² + 8х = 0
-х(х - 8) = 0
х = 0
х = 8
Вроде бы так, но я не уверена