SOLUTION: I am trying to solve for a "to the power of x" equation using a scientific calculator. I have started with an example for which I know the answer How do you use a calculator to

Algebra ->  Exponents -> SOLUTION: I am trying to solve for a "to the power of x" equation using a scientific calculator. I have started with an example for which I know the answer How do you use a calculator to      Log On


   

Question 55681: I am trying to solve for a "to the power of x" equation using a scientific calculator.
I have started with an example for which I know the answer
How do you use a calculator to solve for, for example:
5 to the power of x = 125
Solve for x.
I know x =3 but how do you get the calculator to tell you this!
Ultimately I want to know how to solve for
0.5 = 1 - e to the power of (-8.9*t)
Solve for t.
Calculator crazy,
Heather
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
While finding the power of a number in a calculator is relatively simple (use the caret (^) as in 4^2 = 16), the inverse is not as easy unless your calculator has a logarithm function.
Addressing your example:
5%5Ex+=+125 To find the value of x, you would take the logarithm of both sides.
log%28%285%5Ex%29%29+=+log%28%28125%29%29 But you can simplify the left side because log%28%28a%5Eb%29%29+=+blog%28a%29, so:
xlog%285%29+=+log%28%28125%29%29
x+=+%28log%28125%29%29%2Flog%285%29 = 3