Question

Помогите пожалуйста решить

Answer 1

ОДЗ:

4x+1>0

4x>-1

x> -0,25

$12)log_{2}(4x+1)-log_{2}\frac{1}{8}=5\\\\log_{2}(4x+1)-(-3)=5\\\\log_{2}(4x+1)+3=5\\\\log_{2}(4x+1)=2\\\\4x+1=4\\\\4x=3\\\\x=0,75\\\\Otvet:\boxed{0,75}$

$15)\left \{ {{log_{7}(x+y)=1 } \atop {log_{7}(x-y)=0}} \right.\\\\+\left \{ {{x+y=7} \atop {x-y=1}} \right.\\------\\ 2x=8\\\\x=4\\\\y=7-x=7-4=3\\\\1)x+y=4+3=7>0\\\\2)x-y=4-3=1>0\\\\Otvet:\boxed{(4;3)}$