SOLUTION: Solve for n 400*(1.2^n)-680*(.85^n)=0 "^n =raised to power of n" I used excel solver and found that n=1.54 but how do you do it and show the work? Thanks

Algebra ->  Expressions-with-variables -> SOLUTION: Solve for n 400*(1.2^n)-680*(.85^n)=0 "^n =raised to power of n" I used excel solver and found that n=1.54 but how do you do it and show the work? Thanks      Log On


   

Question 62490: Solve for n
400*(1.2^n)-680*(.85^n)=0 "^n =raised to power of n"
I used excel solver and found that n=1.54 but how do you do it and show the work?

Thanks
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
400*(1.2^n)=680*(.85^n)
1.2^n=1.7(0.85^n)
Take the log of both sides to get:
nlog(1.2) = log1.7 + nlog0.85
n[log(1.2)+log(0.85)]=log(1.7)
n=[log(1.7)]/[log(1.2)+log(0.85)]
n=26.795851...
Cheers,
Stan H.