SOLUTION: Problem is: Solve for x (write answer in calculator ready form): 5^-3x =4. I have gotten it to log (base 5)4 = -3. I know the answer is x = - log4/3log5 but don't know how to

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: Problem is: Solve for x (write answer in calculator ready form): 5^-3x =4. I have gotten it to log (base 5)4 = -3. I know the answer is x = - log4/3log5 but don't know how to      Log On


   

Question 866614: Problem is: Solve for x (write answer in calculator ready form): 5^-3x =4. I have gotten it to log (base 5)4 = -3.
I know the answer is x = - log4/3log5 but don't know how to get the answer. Thanks.
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
b%5Ex=y means log%28b%2Cy%29=x
you are given: 5%5E%28-3x%29=4
in your case b=5, x is actually -3x, and y=4

so you have log%285%2C4%29=-3x

log%285%2C4%29%2F-3=x............in base 10, log%285%2C4%29 will be log%284%29%2Flog%285%29

%28+log%284%29%2Flog%285%29%29%2F-3=x

-+log%284%29%2F3log%285%29=x