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February 8th, 2013, 06:15 AM   #1
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mathematics - Q 8

Hi

can please check my answer for a and b




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February 8th, 2013, 06:50 AM   #2
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Re: mathematics - Q 8

(B) is correct. For (A) you have


Surely, you understand that y' on the left is wrong? From you get but NOT y'= 0.

Differentiating again, ^2- 2yy''- 2cy''= 0" />. Now, going back to ou can get so that . Replace the "c" in with .
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February 8th, 2013, 10:19 AM   #3
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Re: mathematics - Q 8

can explain to me line number 4 and 5

from where you got 2(y)^2 in line 4
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February 9th, 2013, 02:39 PM   #4
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Re: mathematics - Q 8

It's the product rule. We start with The derivative of 2x, with respect to x, is, of course, 2. The derivative of 2yy' is (y&#39+ 2(y)(y'&#39= 2y'^2+ 2yy''" />. The derivative of 2xy' is y'+ 2x(y'&#39= 2y'+ 2xy''" />. Putting those together, the derivative of is .
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