Question

решите уравнения
1) х-√х+3=0
2) х-9√х+20=0

Answer 1

1) x = (√x)²
(√x)² - √x + 3 = 0
D = (-1)² - 4*1*3 = 1 - 12 < 0  нет корней
2)
(√x)² - 9√x + 20 = 0
D = (-9)² - 4*1*20 = 81 - 80 = 1
(√x)₁ = (9 - 1) / 2 = 4 --->  x₁ = 16
(√x)₂ = (9 + 1) / 2 = 5 --->  x₂ = 25