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Qualification => Subject Doubts => GCE AS & A2 Level => Math => Topic started by: yasser37 on April 26, 2011, 04:01:17 pm

Title: p3 doubt
Post by: yasser37 on April 26, 2011, 04:01:17 pm

Hi all

in June 10 p31
Question 9
Part 2

I keep getting x=1

Title: Re: p3 doubt
Post by: EMO123 on April 26, 2011, 04:03:41 pm

You should post these doubt at this link
https://studentforums.biz/math-146/p2-and-p3-doubts-here!!!!!/

Title: Re: p3 doubt
Post by: yasser37 on April 26, 2011, 06:17:41 pm

that's what I did  ??? ???

Title: Re: p3 doubt
Post by: SkyPilotage on April 26, 2011, 08:25:30 pm

Hmm. You equated the answer in part i to zero right?
You have to equate the derivative of part i to zero and ulll get the right answer! Because if u equate part i to zero its as iff ur finding the x-coordinate when the normal to the curve is horizontal! but the want the x-coordinate when the normal's gradient is maximum not equal to zero! I hope u got it.

Title: Re: p3 doubt
Post by: yasser37 on April 27, 2011, 03:54:55 pm

I differentiated the answer in part one and equated to zero
maybe am doing something wrong :S

Title: Re: p3 doubt
Post by: SkyPilotage on April 27, 2011, 05:55:53 pm

Would you like to show me your working?