8-3(4-5х)=20х-34
8-12+15х=20х-34
-5х=-30
х=6
Ответ: 6
16. 2^(5-10x)>1
log₂2^(5-10x)>log₂1
5-10x>0
x<0,5.
17. 16^x>0,125
2^(4x)>1/8
2^(4x)>1/2³
2^(4x)>2⁻³
4x>-3
x>-3/4.
18. 0,5^x>1/128
0,5^x>(0,5)⁷
x<7.
19. 3^(x+1)<9^(4x²)/√27
3^(x+1)<3^(8x²)/3^(3/2)
3^(x+1)<3^(8x²-3/2)
x+1<8x²-3/2
8x²-x-5/2>0 D=81
x=-0,5 x=0,625
(x+0,5)(x-0,625)>0
-∞_____+_____-0,5_____-_____0,625______+_____+∞
x∈(-∞;-0,5)U(0.625;+∞).
.................................................