Question

Корень 2х^2-14х+21 +4=х
Решите B2

Answer 1

√(2x²-14x+21) = x-4

{2x²-14x+21 = (x-4)²

{x-4 >= 0, x >= 4

2x²-14x+21 = x²-8x+16

x²-6x+5 = 0

Так как a+b+c = 0(1-6+5 = 0):

x1 = 1

x2 = c/a = 5/1 = 5

Ответ: x = 5