You are Here: Home >< Maths

# C3 Differentiation

Announcements Posted on
TSR's new app is coming! Sign up here to try it first >> 17-10-2016
1. Not a question on how to do something, but rather, how do you know when to do what? like when to use product rule or quotient rule?

Like I understand the cases when you can't use it, but how do you know which is the best one to use as I could use certain ones with both?

I hope you understand what I'm trying to say?
2. Let f(x) and g(x) be two functions. If we have a function of the form f(x)g(x) then product rule. If we have a function of the form f(x)/g(x) then quotient rule.
3. (Original post by mathematigeek)
Let f(x) and g(x) be two functions. If we have a function of the form f(x)g(x) then product rule. If we have a function of the form f(x)/g(x) then quotient rule.
Yes I understand that, but my point is I could make F(x)/G(x) to F(x)(G(X))^-1 and use product rule, and sometimes it is in fact easier than using quotient rule.
4. (Original post by Xphoenix)
Not a question on how to do something, but rather, how do you know when to do what? like when to use product rule or quotient rule?

Like I understand the cases when you can't use it, but how do you know which is the best one to use as I could use certain ones with both?

I hope you understand what I'm trying to say?
Product rule, used when two functions are multiplied together, hence product.

Quotient rule, used when one function is divided by another. Basically, if you see a dividing line, use the latter.
5. (Original post by Xphoenix)
Yes I understand that, but my point is I could make F(x)/G(x) to F(x)(G(X))^-1 and use product rule, and sometimes it is in fact easier than using quotient rule.
So do what's easier.. but dont be surprised if you lose marks in an exam for using the same technique over and over even when its obvious by the set out of the function which is the intended method.

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: September 26, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### How does exam reform affect you?

From GCSE to A level, it's all changing

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read here first

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams