1
x²+2x≤0
x(x+2)≤0
x=0 x=-2
+ _ +
------------[-2]-------------[0]-------------------
x∈[-2;0]
2
(3x-2)/(5-2x)≤0
x=2/3 x=2,5
_ + _
------------------[2/3]----------(2,5)--------------
x∈(-∞;2/3] U (2,5;∞)
3
{4-x≤2x-5⇒-x-2x≤-5-4⇒-x≤-9⇒x≥9
{8-2x3
x∈[9;∞)