2^(x)*2^(3)+2^(x)*2^(-1)=38
2^3=8
2^(-1)=1/2
2^(x)*(8+(3/2))=38
2^(x)*(19/2)=38
Делим на 19
2^(x)*(1/2)=2
Умножаем на 2
2^(x)=4
2^(x)=2^2
[b]x=2[/b]
2^(x-1+4)+3*2^(x-1)=38,
2^(x-1)*2^(4)+3*2^(x-1)=38,
2^(x-1)*(2^(4)+3)=38,
2^(x-1)*19=38,
2^(x-1)=38:19,
2^(x-1)=2,
2^(x-1)=2^(1),
x-1=1,
x=2.
Ответ: 2.