Math basics › Precalculus
Exponential and log equations
Same base, drop it
If you can write both sides with the same base, the exponents must be equal. 2ˣ = 8 becomes 2ˣ = 2³, so x = 3.
Otherwise take logs
Take ln of both sides and bring the exponent down: ln(aˣ) = x·ln(a). That is what log rules are for.
Check every answer
Log equations produce extraneous solutions constantly. Any answer that makes the inside of a log zero or negative is not a solution, however good the algebra was.