The Student Room Group
What does x4 differentiate to?
Reply 2
When integrating, the way how i remember is is that i add 1 to the power of the term, then divide it by the new power. Also, don't forget to add c at the end, as a constant.

Also, to the second question, x^4 differentiates to 4x^3
increase power by one, divide by new power.
Reply 4
axndx=axn+1n+1+c\displaystyle\int{ax^n}dx=\dfrac{ax^{n+1}}{n+1}+c
For this case a=4, n=3
Reply 5
Hippysnake
increase power by one, divide by new power.


This.

This is the rule for integrating anything which is a multiple of a power of x.

Also, everyone so far has forgotten +C... (edit: this was true when I started typing, but Small123 has since proved me wrong)
cpdavis
Also, to the second question, x^4 differentiates to 4x^3


I was asking the OP, but thanks anyway :p:
Small123
axn=axn+1n+c\displaystyle\int{ax^n}=\dfrac{ax^{n+1}}{n}+c
For this case a=4, n=3


axndx=axn+1n+c\displaystyle\int{ax^n} \mathrm{d}x =\dfrac{ax^{n+1}}{n}+c

:wink:
Reply 8
tommm
This.

This is the rule for integrating anything which is a multiple of a power of x.

Also, everyone so far has forgotten +C... (edit: this was true when I started typing, but Small123 has since proved me wrong)

I didn't get it first time, I luckily edited straight after posting :p:.

electriic_ink
axndx=axn+1n+c\displaystyle\int{ax^n} \mathrm{d}x =\dfrac{ax^{n+1}}{n}+c

:wink:


:o:!!

Note to self: Stare at solution for 1 minute to minimise fails :p:.
Small123
axndx=axn+1n+c\displaystyle\int{ax^n}dx=\dfrac{ax^{n+1}}{n}+c
For this case a=4, n=3

I though it was

axndx=axn+1n+1+c\displaystyle\int{ax^n}dx=\dfrac{ax^{n+1}}{n+1}+c

??
Reply 10
Loz17
I though it was

axndx=axn+1n+1+c\displaystyle\int{ax^n}dx=\dfrac{ax^{n+1}}{n+1}+c

??


So many fails in one post :facepalm:, thanks :o:!
Reply 11
EierVonSatan
What does x4 differentiate to?


Ehh.. apparently I should increase the power by one which would go to make 4^5 but then I divide by the new power? what does that mean/ which bit am i meant to divide? and what about the 3dx bit :s
∫4x^3dx

the DX bit simply means intergrate with respect to x.. this part will make more sense later on but for now leave it alone

youre meant to intergrate all the terms involving x in this expression.. so if you apply the rule to 4x^3, what do you think youll get? raise the power on the x term and then divide by the new power on the x term and see what happens
Reply 13
cpdavis
Also, to the second question, x^4 differentiates to 4x^3

I love how you answered his question even though he was clearly trying to help out OP. Also small123 did accidentally make a mistake and that it should be n+1 on the bottom rather than just n:smile:
Small123
So many fails in one post :facepalm:, thanks :o:!


Dw. I do that all the time!

femmedelala
Ehh.. apparently I should increase the power by one which would go to make 4^5 but then I divide by the new power? what does that mean/ which bit am i meant to divide? and what about the 3dx bit :s



OP, if you have x4x^4 for example, if you divide by the power, you will get x44\frac{x^4}{4}

So, if you have to integrate 4x34x^3 where you increase the power by one then divide the whole thing by the new power, what do you get?
Reply 15
trance addict
∫4x^3dx

the DX bit simply means intergrate with respect to x.. this part will make more sense later on but for now leave it alone

youre meant to intergrate all the terms involving x in this expression.. so if you apply the rule to 4x^3, what do you think youll get? raise the power on the x term and then divide by the new power on the x term and see what happens


Oh so you mean ∫x^4dx ?? :unsure:
femmedelala
Ehh.. apparently I should increase the power by one which would go to make 4^5 but then I divide by the new power? what does that mean/ which bit am i meant to divide? and what about the 3dx bit :s


I asked what x4 differentiated to (not integrated to)...for differentitation you multiply by the old power and take away one away from the power:

ddxxn=nxn1\frac{d}{dx} x^n = nx^{n-1} so in this case ddxx4=4x3\frac{d}{dx} x^4 = 4x^{3} :smile:

As integration is the reverse of differentiation 4x3 must integrate to x4 (+ a constant).

So the opposite rule for integration (as others have stated) is to add one to the power and divide by the new power (old power + 1):

xndx=xn+1n+1+c\displaystyle\int{x^n}dx=\dfrac{x^{n+1}}{n+1}+c
Reply 17
cpdavis
When integrating, the way how i remember is is that i add 1 to the power of the term, then divide it by the new power. Also, don't forget to add c at the end, as a constant.

Also, to the second question, x^4 differentiates to 4x^3


lol you mug :giggle:
femmedelala
Oh so you mean ∫x^4dx ?? :unsure:


yeah but remember to remove the intergral and dx after youve applied the rule since youve intergrated it now.. and add a +c since there are no limits.
Reply 19
Thanks guys, managed to get my head around it, was the DX bit at the end that was the source of confusion but I'm good now :smile:

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