А
Основание меньше 1,значит знак неравенства меняется
(x²-4x-15)/(x+1)≤3
(x²-4x-15)/(x+1)-3≤0
(x²-4x-15-3x-3)/(x+1)≤0
(x²-7x-18)/(x+1)≤0
x²-7x-18=0
x1+x2=7 U x1*x2=-18
x1=9 U x2=-2
x+1=0
x=-1
_ + _ +
--------[-2]----------(-1)---------------[9]---------
x∈(-∞;-2] U (-1;9]
b
8*0,5^2x-17*0,5^x+2≤0
0,5^x=t
8t²-17t+2≤0
D=289-64=225
t1=(17-15)/16=1/8 U t2=(17+15)/16=2
+ _ +
---------[1/8]-----------------[2]----------------
1/8≤t≤2
0,5^x≥1/8⇒x≤3
0,5^x≤2⇒x≥-1
x∈[-1;3]