Check my precalc
posted by Rebekah on .
what is the f inverse of f(x)= ln(x3)
I got y= e^x  4
Solve
8 times 10^(2x7)=3
I do not know how to do this. Do i get 8 and 10 with the same base? How?
Thanks!

f(x) = ln(x3) or
y = ln(x3)
first step of find the inverse is to interchange the x and y variables, so the inverse is
x = ln(y3)
e^x = y3
y = e^x + 3
2.
8 (10^(2x7) ) = 3
10^(2x7) = .375
take log of both sides
log( 10^(2x7) ) = log .375
(2x7) log 10 = log .375, remember log 10 = 1
2x  7 = log .375
x = (7 + log.375)/2 = appr 3.287