Question

Помогите решить уравнения

Answer 1

1.

$\sqrt{x + 4} = x + 2 \\ x + 4 = {x}^{2} + 4x + 4 \\ x = {x}^{2} + 4x \\ x - {x}^{2} - 4x = 0 \\ - {x}^{2} + x - 4x = 0 \\ - 3x - {x}^{2} = 0 \\ - x \times (3 + x) = 0 \\ - x = 0 \\ x = 0 \\ 3 + x = 0 \\ x = - 3 \\ \sqrt{0 + 4} = 0 + 2 \\ \sqrt{ - 3 + 4} = - 3 + 2 \\ 2 = 2 \\ 1 = - 1$

2=2 утверждение верно

1=-1 утверждение ложно

3.

$y = {x}^{3} - 6 {x}^{2} - 15x + 3 \\ y = {0}^{3} - 6 \times 0^{2} - 15 \times 0 + 3 \\ y = 0 - 6 \times 0 - 0 + 3 \\ y = - 0 + 3 \\ y = 3$