How do you solve log516 - log52t = log52log516log52t=log52?

1 Answer
Nov 15, 2015

Remember the logarithm rule: log_(a)(x/y)=log_ax-log_ayloga(xy)=logaxlogay
You can work in reverse:
log516-log52t=log52log516log52t=log52
log(516/(52t))=log52log(51652t)=log52

Now, there are multiple things you could do from here, but the easiest would be to recognize that if loga=logb,a=bloga=logb,a=b.
Therefore, 516/(52t)=5251652t=52.
We can solve for tt.
516=2704t^2516=2704t2
516/2704=t^25162704=t2
sqrt(516/2704)=t5162704=t
sqrt(129/676)=t129676=t

Notice that we only use the positive square root, excluding -sqrt(129/676)129676. We must do this since if we plugged-sqrt(129/676)129676 into log52tlog52t, we would get a negative number, which is impossible.