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# C3 Natural Logs Question watch

1. It's part (iv) of the question that I'm having problems with. The function f is defined by:

(iv) Given that , find the exact value of a.

So this is what I did:

So my answer was a = 125/27. But the answer in the back is a = 98/27. I have no idea how I would get that? I've noticed the book has a few errors, so is this just an error or am I going wrong somewhere?

Thanks very much!
2. is NOT (they are not 'like' terms)

is NOT (they are not 'like' terms)

Thank you - I realise that I just wasn't thinking properly!

I'll have another go.
4. (Original post by AlesanaWill)
It's part (iv) of the question that I'm having problems with. The function f is defined by:

(iv) Given that , find the exact value of a.

So this is what I did:

So my answer was a = 125/27. But the answer in the back is a = 98/27. I have no idea how I would get that? I've noticed the book has a few errors, so is this just an error or am I going wrong somewhere?

Thanks very much!

a^3 - a does not equal a^2
5. (Original post by steve2005)
a^3 - a does not equal a^2
Yes I realised that mistake. But now I've got:

1/3ln (a^3- a / a^2 - a) = ln 5/3

which becomes:

(a^3 -a / a^2 - a) = 125/27

and I'm not getting anywhere. I divided the top and bottom of the fraction by a and then put it into a quadratic equation but that's not helping either. Help?
6. (Original post by AlesanaWill)
Yes I realised that mistake. But now I've got:

1/3ln (a^3- a / a^2 - a) = ln 5/3

which becomes:

(a^3 -a / a^2 - a) = 125/27

and I'm not getting anywhere. I divided the top and bottom of the fraction by a and then put it into a quadratic equation but that's not helping either. Help?
Difference of two squares
7. Thanks very much all. Sorted now.

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