SOLUTION: hi im stuck on logs the question ive got is {{{5^(3x-1)=87}}} we're allowed to use calculators and ive tried the log(5x87) but i think i need the method for this one to work out ot

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: hi im stuck on logs the question ive got is {{{5^(3x-1)=87}}} we're allowed to use calculators and ive tried the log(5x87) but i think i need the method for this one to work out ot      Log On


   

Question 399372: hi im stuck on logs the question ive got is 5%5E%283x-1%29=87 we're allowed to use calculators and ive tried the log(5x87) but i think i need the method for this one to work out others. hope you can help
Found 2 solutions by richard1234, ewatrrr:
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
Taking log of both sides,

log%285%2C+5%5E%283x-1%29%29+=+log%285%2C+87%29

3x+-+1+=+log%285%2C+87%29

x+=+%28log%285%2C+87%29+%2B+1%29%2F3 = 1.25827...

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

5%5E%283x-1%29=87

ln%285%5E%283x-1%29%29=+ln%2887%29

 (3x-1)ln5 = ln87

    3x = ln87/ln5 + 1

     x = (ln87/ln5 + 1)/3 = 1.2583