# Thread: How to find the derivative of this function

1. ## How to find the derivative of this function

$\displaystyle y = 6e^x$

Does the Power Rule apply? Or does $\displaystyle e^x$ stay the same? I tried with the Power Rule and it got confusing and messy.

2. Originally Posted by ImaCowOK
$\displaystyle y = 6e^x$

Does the Power Rule apply? Or does $\displaystyle e^x$ stay the same? I tried with the Power Rule and it got confusing and messy.
$\displaystyle (6e^x)' = 6e^x$

because when doing derivation you are doing derivation only of functions with "x" can do it by chain rule

$\displaystyle (6e^x)' = 6' \cdot e^x + 6\cdot (e^x)' = 0\cdot e^x + 6 \cdot e^x = 6e^x$

3. We haven't learned the chain rule, is there another way? If not, I'll just learn the chain rule.

4. Originally Posted by ImaCowOK
We haven't learned the chain rule, is there another way? If not, I'll just learn the chain rule.
you can look at it like this ...

$\displaystyle (6e^x)' = 6(e^x)' = 6e^x$

because you pull out the constant ... and now you just do derivation of the function with x

5. Originally Posted by ImaCowOK
$\displaystyle y = 6e^x$

Does the Power Rule apply? Or does $\displaystyle e^x$ stay the same? I tried with the Power Rule and it got confusing and messy.
All you need are two things:

1. The derivative of e^x is e^x. (If you have not learned this then there is no point attempting questions that require knowing it).

2. If y = a f(x) then dy/dx = a f'(x).

6. Originally Posted by mr fantastic

If you have not learned this then there is no point attempting questions that require knowing it
Yep, that pretty much explains my class - homework problems on stuff we haven't been taught.

7. Originally Posted by ImaCowOK
Yep, that pretty much explains my class - homework problems on stuff we haven't been taught.
But surely you have a textbook or lecture notes.
Use them. Look up the topic even if you have not seen it in class.

8. Originally Posted by yeKciM
$\displaystyle (6e^x)' = 6' \cdot e^x + 6\cdot (e^x)' = 0\cdot e^x + 6 \cdot e^x = 6e^x$
$\displaystyle (6e^x)' = 6' \cdot e^x + 6\cdot (e^x)' = 0\cdot e^x + 6 \cdot (x)'e^x = 6e^x$
in case $\displaystyle x=-x$ answer would change to $\displaystyle -6e^{-x}$

9. Originally Posted by Revy
$\displaystyle (6e^x)' = 6' \cdot e^x + 6\cdot (e^x)' = 0\cdot e^x + 6 \cdot (x)'e^x = 6e^x$
in case $\displaystyle x=-x$ answer would change to $\displaystyle -6e^{-x}$
you should probably do :

$\displaystyle \displaystyle (Ae^{ax})' = ?$

$\displaystyle \displaystyle (Ae^{-ax})' = ?$

$\displaystyle \displaystyle (x^Ae^{ax})' = ?$

$\displaystyle \displaystyle (A^xe^{ax})' = ?$

Originally Posted by mr fantastic
Given the obvious background of the OP, the previous two replies are less than helpful. Post #5 is all that is required for the OP to understand at this point in time. Product rules etc. are not appropriate for this thread as it will just confuse the OP.

10. Given the obvious background of the OP, the previous two replies are less than helpful. Post #5 is all that is required for the OP to understand at this point in time. Product rules etc. are not appropriate for this thread as it will just confuse the OP.

11. Originally Posted by ImaCowOK
Yep, that pretty much explains my class - homework problems on stuff we haven't been taught.
If that is true, then your problem is with the teacher and I would suggest that you discuss the matter with him/her.

12. Originally Posted by Plato
But surely you have a textbook or lecture notes.
Use them. Look up the topic even if you have not seen it in class.
Originally Posted by mr fantastic
If that is true, then your problem is with the teacher and I would suggest that you discuss the matter with him/her.
I do use the textbook as well as my notes. It's not as easy as that for someone who has never studied calculus before. I came here for help, not for a scolding. Is this not called "Math Help Forum"? If I have the wrong impression of what this site is for and my presence is bugging other users just say so and I'll leave. There's no need to be so insulting when you know nothing about the situation mr fantastic.

I've gotten all that I needed from this thread. Thanks.

13. Originally Posted by ImaCowOK
I do use the textbook as well as my notes. It's not as easy as that for someone who has never studied calculus before. I came here for help, not for a scolding. Is this not called "Math Help Forum"? If I have the wrong impression of what this site is for and my presence is bugging other users just say so and I'll leave. There's no need to be so insulting when you know nothing about the situation mr fantastic.

I've gotten all that I needed from this thread. Thanks.
You're being very defensive. I'm pretty sure they were both trying to help you. Try reading mr fantastic's comment tomorrow and you might see what he was trying to tell you - he didn't mean to insult / scold you at all.

14. I think you have a reading problem.
A Mathematics Help Forum is NOT a “Do it for me home-work” service.
You do understand that this is not a homework service?

15. Originally Posted by ImaCowOK
I do use the textbook as well as my notes. It's not as easy as that for someone who has never studied calculus before. I came here for help, not for a scolding. Is this not called "Math Help Forum"? If I have the wrong impression of what this site is for and my presence is bugging other users just say so and I'll leave. There's no need to be so insulting when you know nothing about the situation mr fantastic.

I've gotten all that I needed from this thread. Thanks.
When someone says
Yep, that pretty much explains my class - homework problems on stuff we haven't been taught.
then I don't think it's unreasonable to say that
your problem is with the teacher and I would suggest that you discuss the matter with him/her
As for the "If" in my statement, it is not unknown for students to, unfairly, blame a teacher for their difficulties.