1
(x²-2x)=a
a²-2a-3≤0
a1+a2=2 U a1*a2=-3
a1=-1 U a2=3
-1≤a≤3
{x²-2x≥-1⇒x²-2x+1≥0⇒(x-1)²≥0⇒x∈R
{x²-2x≤3⇒x²-2x-3≤0⇒(x-3)(x+1)≤0⇒-1≤x≤3
Ответ x∈[-1;3]
2
x²-4x=a
a²+7a+12≤0
a1+a2=-7 U a1*a2=12
a1=-4 U a2=-3
-4≤a≤-3
{x²-4x≥-4⇒x²-4x+4≥0⇒(x-2)²≥0⇒x∈R
{x²-4x≤-3⇒x²-4x+3≤0⇒(x-3)(x-1)≤0⇒1≤x≤3
x∈[1;3]