# Quick Question differentiating logs

KV-1
1. my function is: f(x)=log 1.5 (-.76x+305). f(x)= log base 1.5 of -.76x+305

3. How do i differentiate it? here is what i have so far: (1/((-.76x+305)ln1.5))*(-.76/dx)

## Answers and Replies

Science Advisor
Homework Helper
That's pretty close. (log base 1.5)(-.76x+305) is equal to log(-.76x+305)/log(1.5), right? I assume that's what you are starting from. Now just differentiate it using the chain rule. My only question is what is the '/dx' doing in there?

KV-1
yes, but there seems to be truly no need for the chain rule, as log(1.5) is a number, equal to 0.176091

so it seems i just multiply the derivative of [log base 10 (-0.76x+305)] by that number!

KV-1
((-0.76)(log(e)))/((-0.76x+305)(log(1.5))

thats the answer i think... in case anyone is curious