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Help with differentiating this equation.

I tried quotient rule and regular rule but seem to get the wrong answer. Please explain how you did it.

Screenshot_2016-03-19-17-12-41.png
(edited 8 years ago)
Original post by Jyashi
I tried quotient rule and regular rule but seem to get the wrong answer. Please explain how you did it.

ddx[4x2+5−xx]


I can't understand the expression :s-smilie:
Do you mean 4x^2 + 5 + x^x ?
Reply 3
Sorry guys just updated with question
Reply 4
Original post by zetamcfc
I can't understand the expression :s-smilie:


Just updated the question
Original post by Jyashi
Just updated the question


What is your problem with this? Differentiate the first term normally. Then quotient rule the second.
Reply 6
Original post by Jyashi
Just updated the question


No need for quotient rule: 5xx=5x1=5x11\dfrac{5-x}{x}=\dfrac{5}{x}-1=5x^{-1}-1
What you wrote was nothing like the question but you'd need to rearrange it so the fraction is an integer, 4x^2+ (5-x)(x^-1)
Original post by joostan
No need for quotient rule: 5xx=5x1=5x11\dfrac{5-x}{x}=\dfrac{5}{x}-1=5x^{-1}-1


Not really with it lol :colondollar:
Reply 9
I tried using chain rule and quotient rule but the answer that i need is 8x-5/x^2 which im not getting
Reply 10
Original post by Jyashi
I tried using chain rule and quotient rule but the answer that i need is 8x-5/x^2 which im not getting


Instead of telling us what you're doing, why don't you post out your working instead so we can see what you're actually doing?
Reply 11
Original post by Zacken
Instead of telling us what you're doing, why don't you post out your working instead so we can see what you're actually doing?


Its fine i managed to resolve it. But surprised that i got different answers using the chain rule and quotient rule.
Reply 12
Original post by Jyashi
Its fine i managed to resolve it. But surprised that i got different answers using the chain rule and quotient rule.


They're not different answers if you did both procedures correctly.
Reply 13
Original post by Zacken
They're not different answers if you did both procedures correctly.


Oh i am sure i messed up somewhere there. On a side note can you tell me what is the implicit derivative of ln(y) ? Do you treat y as a constant which would mean derivative of y will be 0 but then do you do 0 dy÷dx?
Reply 14
Original post by Jyashi
Oh i am sure i messed up somewhere there. On a side note can you tell me what is the implicit derivative of ln(y) ? Do you treat y as a constant which would mean derivative of y will be 0 but then do you do 0 dy÷dx?


It is (dy/dx)/y. Differentiating the logarithm of somethins is the derivative of something over the something. In this case the something is y, so d/dx(y) = dy/dx.

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