Замена переменной:t=x²t²=x⁴t²-3t+2≤0t²-3t+2=0D=(-3)²-4*2=9-8=1t₁=(3-1)/2=1t₂=(3+1)/2=2 + - +----------- 1 ------------- 2 ------------- \\\\\\\\\\\\\\\\\t∈[1; 2]1≤t≤21≤x²≤2{x²≥1{x²≤2x²≥1x²-1²≥0(x-1)(x+1)≥0x=1 x= -1 + - +--------- -1 ------------ 1 ------------\\\\\\\\\\\\\ \\\\\\\\\\\\\\\x∈(-∞; -1]U[1; +∞)x²≤2x²-(√2)²≤0(x²-√2)(x²+√2)≤0x=√2 x= -√2 + - +----------- -√2 ---------- √2 ----------- \\\\\\\\\\\\\\x∈[-√2; √2]{x∈(-∞; -1]U[1; +∞){x∈[-√2; √2]⇒ x∈[-√2; -1]U[1; √2]Ответ: [-√2; -1]U[1; √2].