1) 8x+9≤-4x+3⇒12x+6≤0⇒12(x+0.5)≤0⇒x≤-0.5⇒x∈(-∞;-0.5]
2) x²-2x-24≥0⇒(x-6)(x+4)≥0 _+__-4__-___6__+___ x∈(-∞;-4]∪[6;∞)
3)-2x²+2x-7<0⇒x²-x+3.5>0⇒|D=1-14<0|⇒x∈R<br>4)-6x+7≥3x+13⇒9x+6≤0⇒9(x+2/3)≤0⇒x∈(-∞;-2/3]
5) -x²+10x-21≥0⇒x²-10x+21≤0⇒(x-3)(x-7)≤0 _+__3__-__7__+__ x∈[3;7]