Answer
$\log_2{8}=3$
Work Step by Step
Let
$x=\log_2{8}.$
RECALL:
$\log_{a}{y} = b \longleftrightarrow a^b = y.$
Use the definition above to convert the equation to an exponential equation and have
$2^x=8.$
Write each side in base 2 to have
$2^x=2^3.$
The bases are the same, so the exponents must be equal. Thus,
$x=3.$
Therefore $\log_2{8}=3$.