㏒²₅х - ㏒₅х =2 ОДЗ х>0
㏒₅х=a
a²-a-2=0
D=1+8=9
a₁=(1+3)/2=2 ㏒₅х=2 x=5²=25
a₂=(1-3)/2=-1 ㏒₅х = -1 x=5⁻¹ =1/5
㏒₂х/4 = 15 / (㏒₂х/8 -1 ) ОДЗ х>0
㏒₂х- ㏒₂4 = 15 / (㏒₂х- ㏒₂8 -1 )
㏒₂х - 2 = 15 / (㏒₂х - 3 -1 )
㏒₂х - 2 = 15 / (㏒₂х - 4 )
(㏒₂х - 2)*(㏒₂х - 4 ) = 15
㏒²₂х -6㏒₂х+8 =15
㏒²₂х -6㏒₂х -7 = 0 ㏒₂х =a
a²-6a-7=0
D=36+28=64
a₁=(6+8)/2=7 ㏒₂х = 7 x₁=2⁷ =128
a₂=(6-8)/2=-1 ㏒₂х = -1 x₂=2⁻¹ =1/2