18xy^2-2xz^2=2x(9y^2-z^2)=2x*(3y-z)(3y+z).
(√(2x+1))²=5² ОДЗ: 2х+1≥0 2х≥-1 х≥-1/2 х∈[-1/2;+∞).
<span>y=cos2x-6x-2 (6х в квадрате)</span>
<span>y'=-2sin2x-6-24x</span>
{6x-3≥3
{-5x≤-10
6x-3≥3
6x≥3+3
6x≥6
x≥6 : 6
х≥1
-5х≤-10
х≥ -10 : (-5)
х≥2
\\\\\\\\\\\\\\\\\\\\\\\\\\
--------- 1 --------- 2 ----------
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x≥2 или х∈[2; +∞)