C1 Differentiation Question
http://www.edexcel.com/migrationdocuments/QP%20GCE%20Curriculum%202000/January%202013%20-%20QP/6663_01_que_20130114.pdf
Edexcel, Jan 2013.
Question 11(b). I'm thinking there should surely be 2 possible answers, as (1/4)^1/2 = +-1/2
If you use +1/2, you get the answer in the mark scheme. However, if you use -1/2, you get a completely different answer.
Surely the second answer is still a correct answer, if not, could someone explain why?
Edexcel, Jan 2013.
Question 11(b). I'm thinking there should surely be 2 possible answers, as (1/4)^1/2 = +-1/2
If you use +1/2, you get the answer in the mark scheme. However, if you use -1/2, you get a completely different answer.
Surely the second answer is still a correct answer, if not, could someone explain why?
It is true that squaring 1/2 or -1/2 gives 1/4, but when you see a square root sign alone - purely by convention - it means the positive square root.
Original post by aking144
I tried the question and replied as soon as possible : This is what i got 
That all looks fine to me
Original post by aking144
11c answer anyway : 
Nice one, that looks correct as well. This was actually my C1 paper, not too bad actually! (I lost my marks on the tangent question though
)Original post by Robbie242
Nice one, that looks correct as well. This was actually my C1 paper, not too bad actually! (I lost my marks on the tangent question though )
)I'm doing AS maths now, so this is basically revision for me and helps people out so good karma XD
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