If the starting equation is
4²<em>ˣ</em> - 4 = 1
first move the 4 on the left to the right side:
4²<em>ˣ</em> = 5
Take the base-4 logarithm of both sides:
log₄(4²<em>ˣ</em> ) = log₄(5)
Drop the exponent on the left, using the property :
2<em>x</em> log₄(4) = log₄(5)
Now for any <em>b</em>, so
2<em>x</em> = log₄(5)
Solve for <em>x</em> by dividing both sides by 2:
<em>x</em> = 1/2 log₄(5)
You can also express this as
<em>x</em> = log₄(√5)
to make the solution slightly more compact.
You can also use the change-of-base identity to rewrite the solution as
<em>x</em> = log(5) / (2 log(4))
where the base of the logarithm is arbitrarily chosen. Then
<em>x</em> = log(5) / log(4²)
<em>x </em>= log(5) / log(16)
<em>x</em> = log₁₆(5)