a) \(4^{x^{ }}=64\)
\(\Rightarrow4^x=4^3\)
\(\Rightarrow x=3.\)
b) Vì \(35⋮x\)
\(\Rightarrow x\inƯ\left(35\right)=\left\{1;5;7;35\right\}\)
Vậy \(x\in\left\{1;5;7;35\right\}\)
c) \(135-\left(x-5\right)=105:3\)
\(\Leftrightarrow\)\(135-\left(x-5\right)=35\)
\(\Leftrightarrow x-5=135-35\)
\(\Leftrightarrow x-5=100\)
\(\Leftrightarrow x=100+5\)
\(\Leftrightarrow\) \(x=105.\)
d) Vì \(x⋮25\)
\(\Rightarrow x\in B\left(25\right)=\left\{0;25;50;75;100;...\right\}\)
Mà \(x< 100\)
\(\Rightarrow x\in\left\{0;25;50;75\right\}\)
