А)
При 13x-6x²-5≥0
6x²-13x+5 ≤0
D=169-4·6·5=49
x₁=(13-7)/12=1/2; x₂=(13+7)/12=5/3;
1/2 ≤ x ≤ 5/3
Б)
При 18-2x²-5х≥0
2x²+5х-18 ≤0
D=25-4·2·(-18)=169
x₁=(-5-13)/4=-9/2; x₂=(-5+13)/4=2;
-9/2 ≤ x ≤ 2
