Derivatives w/ In: for y = In x-3x, is y equal to 1/x - 3?

[Tazman]

Here is my problem

1) y = In x-3x

Would my answer be 1/x - 3

and

2) y=In(4x+3)

Would my answer be 4/(4x + 3).

If you go the same answer, can you show your work - so I know that I am doing it correctly or incorrectly if that is the case.

Help would be appreciated. Taz

 

[o_O]

Re: Derivatives Involving In

1. Yep. Just take the derivative of each term.
\(\displaystyle (lnx - 3x)' = (lnx)' - (3x)' = \frac{1}{x} - 3\)


2. Yep.
\(\displaystyle \left[ln(4x + 3)\right]' = \frac{1}{4x + 3} \cdot (4x + 3)'\)

\(\displaystyle = \frac{1}{4x + 3} \cdot 4\)

\(\displaystyle = \frac{4}{4x + 3}\)

Just like you had it.

 

[stapel]

If you go the same answer, can you show your work...?

If you're getting the right answer (like is in the back of the book), why would you need to be given all the steps...? :shock:

Eliz.