Verified answer

√(x²+34)≥6;

x²+34≥36;

x²≥2;

x ∈ (-∞;-√2] ∪ [√2;∞);

2) ОДЗ: 8-x≥0; x≤8;

8-x=0; x=8;

x²-x-6 ≤ 0;

D=1+4*6=25;

x=(1+5)/2=3;

x=(1-5)/2=-2;

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x ∈ [-2;3] ∪ {8};

3) x+4≥0; x≥-4;

x+4<25;

x<21;

x ∈ [-4;21);

4) x²-15≥0; x²≥15;

x²-15≥9;

x²≥24;

x ∈ (-∞;-2√6] ∪ [2√6;∞)