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# As maths

+1
71
7
+399

Differentiate

5x - 7 + 2x-1/2 + 3x-1

Rauhan  Nov 25, 2017
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#1
+26366
+3

"Differentiate 5x - 7 + 2x-1/2 + 3x-1"

$$\frac{d}{dx}5x=5\\\frac{d}{dx}7=0\\\frac{d}{dx}2x^{-1/2}\rightarrow (-1/2)2x^{-1/2-1}\rightarrow -x^{-3/2}\\ \frac{d}{dx}3x^{-1}\rightarrow (-1)3x^{-1-1}\rightarrow -3x^{-2}\\$$

I'll leave you to add these together!

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Alan  Nov 25, 2017
#2
+399
+2

I am confused at what the answer sheet says

http://egyptigstudentroom.com/pastpapers/edexcel/alevel/gce/Math/Jan%202008/ms//8371_9374_GCE_Mathematics_msc_20080306_UA019869.pdf go to page number 9

Rauhan  Nov 25, 2017
#3
+26366
+2

I’m not surprised - it is the muddiest explanation I’ve ever come across!

Do you understand the derivatives in my previous reply, or do you need more explanation?

Alan  Nov 25, 2017
#4
+399
+2

I understood how u did but i cant confirm ur answer with the answer of the answer sheet

Rauhan  Nov 25, 2017
#5
+26366
+2

The answer sheet has the results as indicated by the red boxes below (you still need to add them together):

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Alan  Nov 25, 2017
#6
+399
+3

So the answer is 5 - x-3/2 - 3x-2

Rauhan  Nov 25, 2017
#7
+26366
+3

Correct!

Alan  Nov 25, 2017

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