# AQA C3 What type of integration is this question asking for?Watch

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#1
Hi, would anybody be able to tell me the integration topic or method to solve this question described by the mark scheme, as I didn't have a clue how to answer the question and need more practise.
The question is 8a from the AQA C3 January 2013 paper here:

And the mark scheme being

I usually just read the mark scheme and work it out but its using k for some reason as well as the exponential 1 just disappearing, if anyone can tell me the integration type this answer requires it will be greatly appreciated, thank you
0
3 years ago
#2
'Recognition'. You know that the differential of e^(kx) = ke^(kx) so you 'work backwards'.

Also, how can you write x^(1-a) as x^(...) * x^(...)? Then for e^(1-a) it will be the same logic.

(Original post by Sayless)
x
0
3 years ago
#3
(Original post by Sayless)
x
As per SeanFM - you should recognise that
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#4
(Original post by SeanFM)
'Recognition'. You know that the differential of e^(kx) = ke^(kx) so you 'work backwards'.

Also, how can you write x^(1-a) as x^(...) * x^(...)? Then for e^(1-a) it will be the same logic.
yeah so i simplify it to:
integral of e x e^(-2x)
now what do i do I don't know how to approach this types of questions even after I simplify it to that,
I know how to do e^2x or 2e^4x differentiation and integration but I don't know when there are 2e's timesed together
0
3 years ago
#5
(Original post by Sayless)
yeah so i simplify it to:
integral of e x e^(-2x)
now what do i do I don't know how to approach this types of questions even after I simplify it to that,
I know how to do e^2x or 2e^4x differentiation and integration but I don't know when there are 2e's timesed together
is just a number so you need only integrate .
0
3 years ago
#6
Standard Patterns
0
3 years ago
#7
(Original post by Sayless)
yeah so i simplify it to:
integral of e x e^(-2x)
now what do i do I don't know how to approach this types of questions even after I simplify it to that,
I know how to do e^2x or 2e^4x differentiation and integration but I don't know when there are 2e's timesed together
e is a constant and it does not depend on x.
0
#8
(Original post by Zacken)
is just a number so you need only integrate .
ah right, I thought that if I took e out of the integrand it would mean I would have to take e out of e^(-2x)
didn't think it worked that way but now it makes sense if its timsing, when I did it I did
integral of e/e^(2x)
which i couldnt make sense of
0
3 years ago
#9
(Original post by Sayless)
ah right, I thought that if I took e out of the integrand it would mean I would have to take e out of e^(-2x)
didn't think it worked that way but now it makes sense if its timsing, when I did it I did
integral of e/e^(2x)
which i couldnt make sense of
Have you managed to solve the problem now?
1
#10
(Original post by Zacken)
Have you managed to solve the problem now?
I solved it but I had to keep e outside the integrand the whole time and the integral,

I don't know what is e*-1/2(e)^-2x
0
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