Thread: finding the vaule of a raised power

I have the following

12.0*1.08^x =25.0

I need to find the value of x but Im lost on how its done.

Dave

Originally Posted by davellew69

I have the following

12.0*1.08^x =25.0

I need to find the value of x but Im lost on how its done.

Dave

1. Divide through by 12.0.

2. Actually you have an exponential term at the LHS so transform the RHS into an exponential term with the same base:

............ So

3. To get an approximate value for x use the base change formula:



Use your calculator.

can this be done by using algebra?

That is algebra.

I would simply use log base 10. No need to change.
log 12 + x(log 1.08) = log 25
x= 9.5

1.08^x = 25/12

x = log(25/12) / log(1.08)

If a^x = b then x = log(b) / log(a) : tattoo that on your wrist!