1.3²ˣ⁺⁶>81, 81=3⁴,
3²ˣ⁺⁶>3⁴, 2x+6>4,2x>4-6,2x>-2, x>-1, x∈(-1;+∞)
2.(1/4)^(x²-6x+5)>1/64, (1/64=1/4) ³,
(1/4)^(x²-6x+5)>(1/4)³
x²-6x+5-3<0, x²-6x+2<0,D=6²-4·2=36-8=28,√D=√28=2√7<br>x₁=(6+2√7)/2=3+√7,x₂=3-√7, (x-3-√7)(x-3+√7)<0<br> x∈(3-√7;3+√7)
3.6^(x²+8x)<1/36,1/36=1/6²=6⁻², x²+8x+8<0, D=8²-4·8=64-32=32,√D=32=4√2<br>x₁=(-4+4√2)/2=-2+2√2, x₂=(-4-4√2)/2=-2-2√2
x∈(-2-2√2;-2+2√2).