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A-Level Maths Differentiation

Where / have I gone wrong in the question below?

The answer I've got isn't in exact form and can't seem to find mistake!
(edited 3 years ago)
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davros
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Original post by annonymous2394
Where / have I gone wrong in the question below?

The answer I've got isn't in exact form and can't seem to find mistake!

I haven't checked your working, but I would have thought that an answer could involve logarithms (ln4 or 2ln2) and still be exact!

Do you have the textbook / mark scheme answer?
4^x/(2x) does not equal 2^x/x...
Original post by annonymous2394
Where / have I gone wrong in the question below?

The answer I've got isn't in exact form and can't seem to find mistake!

(4^x)/2 <> 2^x
Thanks - I've now got almost the same but the 2nd last line is now (2x(4^x ln4) -4^x*2) / 2x^2

Answer comes out as 3.545.... when i sub x=2 in , do I have to simplify to get the exact form ?
Original post by annonymous2394
Thanks - I've now got almost the same but the 2nd last line is now (2x(4^x ln4) -4^x*2) / 2x^2

Answer comes out as 3.545.... when i sub x=2 in , do I have to simplify to get the exact form ?

For exact form, you will want an ln4 in your answer (don't make that a decimal!)

Mind uploading your new working? I found I only needed the product rule for this Q :smile: Also is the 3.545 your answer or the markschemes?
(edited 3 years ago)
I would expect an answer in terms of ln 2 really (ln 4 = 2 ln 2).

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