1
x²+5x+6≥0
x1+x2=-5 U x1*x2=6⇒x1=-3 U x2=-2
x∈(-∞;-3] U [-2;∞)
2
(9-x²)/(x-2)>0
(3-x)(3+x)/(x-2)>0
x=3 x=-3 x=2
+ _ + _
-------------(-3)---------------(2)----------(3)-----------------
x∈(-∞;-3) U (2;3)
3
{36-x²≥0⇒(6-x)(6+x)≥0 x=6 U x=-6 -6≤x≤6
{x+5>0⇒x>-5
{log(22)(x+5)≠0⇒x+5≠1⇒x≠-4
x∈(-5;-4) U (-4;6]
4
{-x²+x+2≥0⇒x²-x-2≤0 x1+x2=1 U x1*x2=-2 -1≤x≤2
{cosx>0⇒-π/2+2πnx∈(-π/3;π/2)