Edexcel C4 June 2014- OFFICIAL THREAD

Original post by Beasttty

integration y times dx/dt
formula in the textbook in that chapter

no that's fine
when you do that you end up having to integrate 2^t - 1 or something

how the hell do you intergrate 2^t, or a^x or any number to the power of x/t/b/abcxyz looool

Reply 383

Original post by #FutureDentist

It's something you should know:
a^x differentiated is ln(a)a^x

isn't it lna^(a^x) = a^xlna?

(edited 9 years ago)

Reply 384

Original post by #FutureDentist

It's something you should know:
a^x differentiated is ln(a)a^x

but thats when you differentiate it, how do you integrate it?

Reply 385

JacobAlevels

7

Original post by ilikebigbuttshaha

but thats when you differentiate it, how do you integrate it?

I was stuck on that too. Apparently the integral of a^x is a^x/lna http://www.youtube.com/watch?v=pmwnldQ2Mik (5:30)
I have yet to work out how that is. Probably some sort of reverse differentiation or something

Reply 386

Original post by JacobAlevels

I was stuck on that too. Apparently the integral of a^x is a^x/lna http://www.youtube.com/watch?v=pmwnldQ2Mik (5:30)
I have yet to work out how that is. Probably some sort of reverse differentiation or something

look at the differential of a^x = a^xlna, do you now see why integrating it is a^x/lna?

if you aren't sure how to integrate something, you differentiate it first and then check and adjust any constants to get back to what you're integrating..

(edited 9 years ago)

Reply 387

JacobAlevels

7

Original post by mightyfrog2_10

look at the differential of a^x = a^xlna, do you now see why integrating it is a^x/lna?

if you aren't sure how to integrate something, you differentiate it first and then check and adjust any constants to get back to what you're integrating..

I did look at the differential of a^x and I tried rearranging the formula but I couldn't see how the integral can be that.
Or is it because the differential is MULTIPLIED by lna, so the integral should be divided by lna?

Reply 388

Original post by JacobAlevels

Or is it because the differential is MULTIPLIED by lna, so the integral should be divided by lna?

yep.

Reply 389

Dilzo999

19

Original post by ilikebigbuttshaha

guys have you tried to Jan 13, the parametric question, but the last part where you had to find the area under the curve.
mad baffed

I did that, wasn't that hard if you understand integration.

Reply 390

Original post by Dilzo999

I did that, wasn't that hard if you understand integration.

i never said i understood integration? lol

Reply 391

Original post by JacobAlevels

I was stuck on that too. Apparently the integral of a^x is a^x/lna http://www.youtube.com/watch?v=pmwnldQ2Mik (5:30)
I have yet to work out how that is. Probably some sort of reverse differentiation or something

yeah same i don't understand how to get to that :/

Reply 392

Original post by mightyfrog2_10

yep.

lol um ok *nods but has no idea what is going on*

can you explain that?

Reply 393

adi.96

Original post by ilikebigbuttshaha

yeah same i don't understand how to get to that :/

It's just another integral you need to know, we're screwed up, there are too many to learn :/

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Reply 394

Faye_m

I hate c4 sooooo much right now.... Anyone else feeling this way?

Reply 395

Original post by ilikebigbuttshaha

lol um ok *nods but has no idea what is going on*

can you explain that?

The way I understand it is if you don't know how to integrate, differentiate first and then think how you're going to get the thing you're integrating. So, differential of a^x = a^xlna, therefore the integral of a^x is a^x/lna.

if you aren't sure how to integrate something, you differentiate it first and then check and adjust any constants to get back to what you're integrating..

I hope this makes sense!

Reply 396

Mutleybm1996

19

Original post by Faye_m

I hate c4 sooooo much right now.... Anyone else feeling this way?

I haven't even looked at C4 yet :/

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Reply 397

Original post by mightyfrog2_10

The way I understand it is if you don't know how to integrate, differentiate first and then think how you're going to get the thing you're integrating. So, differential of a^x = a^xlna, therefore the integral of a^x is a^x/lna.

if you aren't sure how to integrate something, you differentiate it first and then check and adjust any constants to get back to what you're integrating..

I hope this makes sense!

omg yes that makes so much sense! thats so helpful actually, because sometimes theres stuff you can't intergrate by inspection, but if you do your method it works!

omg thanks lol

Reply 398

Original post by adi.96

It's just another integral you need to know, we're screwed up, there are too many to learn :/

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yeah exam solutions guy said it's in the textbook but it's not in mine loool :') i know right, theres so many! :mad:

Reply 399