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If I understand you correctly, you have been given the following exponential equation:

. . . . .

I'm guessing they just want you to take the log of each side of the above equation...? At that point, you'll need to apply somelog rulesto split apart the log form into individual log terms. Then see which answer option matches what you'd started with.

One method would be to applythe Quadratic Formulato each of the equations (or at least check the value of the Formula's disciminant for each equation), and see which one gives you the required result.

Use what you know aboutlogarithmsto recall which argument gives the same log value, regardless of the base. For instance, compare the graphs of the common (base-ten) log and the natural (base-e) log, and see where the two lines cross....