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Mathematics: Post your doubts here!

U

unique111

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salvatore said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w10_qp_33.pdf
qn 9(ii), I've shown my attempt working below. Could someone please tell me where I've gone wrong? I'll be grateful..

dA/dt = k√(2A - 5)
dt/dA = 1 / k√(2A - 5)
k dt = 1/(√2A-5) dA
kt + c = √(2A-5) / (1/2)
kt + c = 2√(2A-5)
t = 0, A = 7
c = 2√9
c = 6
Click to expand...
You haven't gone wrong anywhere. Just continue. Now by replacing t=10 and A=27 find the value of k. Then by replacing t=20 find the Area. :)
 
Beyond650

Beyond650

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MaRyy xD said:
Thankyouuuuuuuuuuuuuu mannn.. I will see it later. mmm do we have to draw the arg diagram on a graph pper in the exam or what?
Click to expand...
On the answer booklet. Unless it is explicitly stated to draw on a graph paper it is best practice to simply draw on the answer booklet since the examiners only want "sensible" diagrams and it looks neater. I asked my friends about this before and they said the same thing. The only the time when I will possibly use a graph paper is if I have to draw a cumulative frequency curve for the S1 paper.
(Also I think you are thanking the wrong person. panoramafolks' answer helped me loads as well.)
 
salvatore

salvatore

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unique111 said:
You haven't gone wrong anywhere. Just continue. Now by replacing t=10 and A=27 find the value of k. Then by replacing t=20 find the Area. :)
Click to expand...
Thank you for your reply.
The marking scheme got the value of C as 3 (I got 6). They also got the value of K as 0.4 (I got 0.4). You must've noticed that I got half their values.. so I've messed up in one tiny bit of the question. I'll appreciate if you could take a closer look at my solution
 
MaRyy xD

MaRyy xD

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Beyond650 said:
On the answer booklet. Unless it is explicitly stated to draw on a graph paper it is best practice to simply draw on the answer booklet since the examiners only want "sensible" diagrams and it looks neater. I asked my friends about this before and they said the same thing. The only the time when I will possibly use a graph paper is if I have to draw a cumulative frequency curve for the S1 paper.
(Also I think you are thanking the wrong person. panoramafolks' answer helped me loads as well.)
Click to expand...
-______- Both were good and i liked both posts. I just chose one of the posts randomly and said thanks.
 
Beyond650

Beyond650

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MaRyy xD said:
Oh and my friend said to use a graph paper so it will be more accurate.
Click to expand...
My friend's reply was:
"its better to follow the paper guidelines
if its written to draw it on the answer booklet then draw it there
otherwise the paper will be fine if nothing is written then do it on the answer booklet since it looks neater and u have more space so even if u screw up nothing matters"

I am prone to to making mistakes in argand diagrams so I will be using the answer booklet. But yeah, I haven't heard of any prohibitions or read about any penalties for drawing on answer booklet in marking scheme so either way is fine. Ultimately, it's everyone's personal choice.
 
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