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Chain rule or product rule?

How would you differentiate y = 6x(1 + x^2 )^2

I'm not sure in what situation you use chain rule and in what situation you would use product rule?

If it was y = 6(1 + x^2 )^2
..could I use chain rule?

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Original post by Peanut247
How would you differentiate y = 6x(1 + x^2 )^2

I'm not sure in what situation you use chain rule and in what situation you would use product rule?

If it was y = 6(1 + x^2 )^2
..could I use chain rule?


You would use both

Though, tbh, I would just multiply that out
Reply 2
Original post by TenOfThem
You would use both

Though, tbh, I would just multiply that out


What do you mean you would use both?
Original post by Peanut247
What do you mean you would use both?


You have a product so you need to use the product rule

One of the functions is a function of a function so that would need the chain rule
Original post by Peanut247
How would you differentiate y = 6x(1 + x^2 )^2

I'm not sure in what situation you use chain rule and in what situation you would use product rule?

If it was y = 6(1 + x^2 )^2
..could I use chain rule?

You can use whatever rule you like. y(x)=6(1+x2)2y(x) = 6(1+x^2)^2 requires first the use of linearity of the derivative, to obtain y(x)=6ddx(1+x2)2y'(x) = 6 \dfrac{d}{dx} (1+x^2)^2, then you could use chain to get y(x)=6×2(1+x2)ddx(1+x2)y'(x) = 6 \times 2 (1+x^2) \dfrac{d}{dx} (1+x^2).

Alternatively, you could use product: y(x)=6(1+x2)(1+x2)y(x) = 6 (1+x^2) (1+x^2) means y(x)=6(1+x2)ddx(1+x2)+6(1+x2)ddx(1+x2)y'(x) = 6 (1+x^2) \dfrac{d}{dx}(1+x^2) + 6 (1+x^2) \dfrac{d}{dx} (1+x^2).

(By the way, y(x)=6x(1+x2)2=ddx(1+x2)3y(x) = 6x (1+x^2)^2 = \dfrac{d}{dx} (1+x^2)^3 by chain rule. It doesn't help here, but some problems are made easier if you know that the function in question is the derivative of something.)
Original post by Smaug123
You can use whatever rule you like. y(x)=6(1+x2)2y(x) = 6(1+x^2)^2 requires first the use of linearity of the derivative, to obtain y(x)=6ddx(1+x2)2y'(x) = 6 \dfrac{d}{dx} (1+x^2)^2, then you could use chain to get y(x)=6×2(1+x2)ddx(1+x2)y'(x) = 6 \times 2 (1+x^2) \dfrac{d}{dx} (1+x^2).

Alternatively, you could use product: y(x)=6(1+x2)(1+x2)y(x) = 6 (1+x^2) (1+x^2) means y(x)=6(1+x2)ddx(1+x2)+6(1+x2)ddx(1+x2)y'(x) = 6 (1+x^2) \dfrac{d}{dx}(1+x^2) + 6 (1+x^2) \dfrac{d}{dx} (1+x^2).

(By the way, y(x)=6x(1+x2)2=ddx(1+x2)3y(x) = 6x (1+x^2)^2 = \dfrac{d}{dx} (1+x^2)^3 by chain rule. It doesn't help here, but some problems are made easier if you know that the function in question is the derivative of something.)


You seem to be differentiating a different question

Then you are referencing integration rules ... Why?
(edited 9 years ago)
Original post by Peanut247
How would you differentiate y = 6x(1 + x^2 )^2

I'm not sure in what situation you use chain rule and in what situation you would use product rule?

If it was y = 6(1 + x^2 )^2
..could I use chain rule?

Fairly sure you can use just use chain for the second one
Original post by TenOfThem
You seem to be differentiating a different question

Then you are referencing integration rules ... Why?


No he has not. Please read OP fully.

Also, he merely made a comment on the integration bit...noting that in this particular case it didnt help but can sometimes be useful in such a problem.
Reply 8
Original post by Smaug123
You can use whatever rule you like. y(x)=6(1+x2)2y(x) = 6(1+x^2)^2 requires first the use of linearity of the derivative, to obtain y(x)=6ddx(1+x2)2y'(x) = 6 \dfrac{d}{dx} (1+x^2)^2, then you could use chain to get y(x)=6×2(1+x2)ddx(1+x2)y'(x) = 6 \times 2 (1+x^2) \dfrac{d}{dx} (1+x^2).

Alternatively, you could use product: y(x)=6(1+x2)(1+x2)y(x) = 6 (1+x^2) (1+x^2) means y(x)=6(1+x2)ddx(1+x2)+6(1+x2)ddx(1+x2)y'(x) = 6 (1+x^2) \dfrac{d}{dx}(1+x^2) + 6 (1+x^2) \dfrac{d}{dx} (1+x^2).

(By the way, y(x)=6x(1+x2)2=ddx(1+x2)3y(x) = 6x (1+x^2)^2 = \dfrac{d}{dx} (1+x^2)^3 by chain rule. It doesn't help here, but some problems are made easier if you know that the function in question is the derivative of something.)


But when I differentiate y= 6x(1+ x^2)^2 using chain rule and the product rule I get different answers..
Original post by newblood
No he has not. Please read OP fully.

Also, he merely made a comment on the integration bit...noting that in this particular case it didnt help but can sometimes be useful in such a problem.


If you say so
Original post by Peanut247
But when I differentiate y= 6x(1+ x^2)^2 using chain rule and the product rule I get different answers..


Once again ... You need to use both but it would be better to multiply it out


Can I check .... Since I have been told that I have misread

You are differentiating 6x(1+x^2)^2 and none of those x are a multiplication sign ... Or ?
Original post by TenOfThem
If you say so


There is no need for attitude. Please try to be more helpful on the maths forum in future :smile:
Original post by newblood
There is no need for attitude. Please try to be more helpful on the maths forum in future :smile:


No attitude here ... We clearly have a different understanding of this thread ... As for your second point ... Are you serious
Reply 13
Original post by TenOfThem
Once again ... You need to use both but it would be better to multiply it out


Can I check .... Since I have been told that I have misread

You are differentiating 6x(1+x^2)^2 and none of those x are a multiplication sign ... Or ?

Yes none of them are multiplication signs sorry.
So do you mean you would use chain regarding (1+x^2)^2 within the product rule?
Original post by Peanut247
Yes none of them are multiplication signs sorry.
So do you mean you would use chain regarding (1+x^2)^2 within the product rule?


Exactly :smile:
Original post by TenOfThem
No attitude here ... We clearly have a different understanding of this thread ... As for your second point ... Are you serious


Please lose the attitude. If you have nothing useful to contribute to help OP, then please dont at all :smile:
Original post by newblood
Please lose the attitude. If you have nothing useful to contribute to help OP, then please dont at all :smile:


I am not sure what your issue is


If you read this thread you will see that my posts have led to the OP understanding how to solve the question

You posts, on the other hand have simply been aimed at criticising me



So ...
Reply 17
Original post by TenOfThem
Exactly :smile:

Ah so you can't just use chain rule by itself to differentiate it... Thank you :smile:
I was trying to do the "quick chain rule" method
(edited 9 years ago)
Original post by Peanut247
Ah so you can't just use chain rule by itself to differentiate it... Thank you :smile:


That is correct ... Chain rule is used when we have a function of a function

The 6x was separate to this and needed the product rule
Original post by newblood
There is no need for attitude. Please try to be more helpful on the maths forum in future :smile:

(Psst - TenOfThem is one of the more prolific helpers on this thread :smile: )

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