- #1

silvershine

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## Homework Statement

Find the value of the constant, k, when f(x) = ln(5x-3)^k and f'(1) = 4

## Homework Equations

f(x) = ln(5x-3)^k

f'(1) = 4

## The Attempt at a Solution

I've tried:

f'(x) = [kln(5x-3)^(k-1)] [1/(5x-3)] (5)

And when I simplified that, I got

f'(x) = 5kln(5x-3)^(k-1) / (5x - 3)

I tried plugging in 4 and 1 so that

4 = 5kln(2)^(k-1) / 2

8 = 5kln(2)^(k-1)

8/5 = kln(2)^(k-1)

And now I'm stumped.

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