1
x∈(-∞;∞)
2
{3+x≠0⇒x≠-3
{5-x≠0⇒x≠5
x∈(-∞;-3) U (3;5) U (5;∞)
3
x-1/4x²≥0
x(1-1/4x)≥0
x=0 U x=4
x∈[0;4]
4
3x²-4x+1≠0
D=16-12=4
x1≠(4-2)/6=1/3 U x2≠(4+2)/6=1
x∈(-∞;1/3) U (1/3;1) U (1;∞)
5
3x²-3x-6>0
x²-x-2>0
x1+x2=1 U x1*x2=-2
x1=-1 U x2=2
x∈(-∞;-1) U (2;∞)
6
{3+x≥0⇒x≥-3
{x-7≠0⇒x≠7
x∈[-3;7) U (7;∞)
7
{x-1≠0⇒x≠1
{2x²-x-3≤0⇒-1≤x≤1,5
D=1+24=25
x1=(1-5)/4=-1 U x2=(1+5)/4=1,5
x∈[-1;1) U (1;1,5]