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Can anyone help with C1 differentiation?

Hi, I'm currently having a problem with this one question, I have done parts A and B, but using the same method with C I seem to keep getting the wrong answer, can anyone help?

ImageUploadedByStudent Room1473600689.642359.jpg

ImageUploadedByStudent Room1473600689.642359.jpg

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Reply 1

Kevin De Bruyne

Original post by Eden00

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Please show your working :h:

Reply 2

RDKGames

Study Forum Helper

Original post by Eden00

Hi, I'm currently having a problem with this one question, I have done parts A and B, but using the same method with C I seem to keep getting the wrong answer, can anyone help?

Posted from TSR Mobile

What's wrong with it? The power decreases by 1 and

\frac{3}{2}-1=\frac{1}{2}

if that's what you're struggling with?

Reply 3

hellomynameisr

If its the fractional power that is making it hard for you, lets stick a 1 in front of the x. Now you can differentiate it how you did the other ones; 1 * 3/2 then subtract 1 from the power.

Reply 4

Eden00

It's not the differentiation part it's the finding the points.

The answer is (16,-31) and I'm unsure how to get there

EDIT: I know in the photo it's -5, but I meant it to be 5, I rewrote my workings to post quickly and made the mistake :wink:

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(edited 7 years ago)

ImageUploadedByStudent Room1473602166.472313.jpg139.1KB

Reply 5

solC

Original post by Eden00

It's not the differentiation part it's the finding the points.

The answer is (16,-31) and I'm unsure how to get there

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When you differentiate a constant it disappears remember

Reply 6

Eden00

Original post by solC

When you differentiate a constant it disappears remember

I'm an idiot... I'll have a go now and see what I get

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Reply 7

Eden00

Original post by solC

When you differentiate a constant it disappears remember

I got rid of the constant the first time I attempted it, the second time I didn't but I'm still running into the same problem.

ImageUploadedByStudent Room1473602479.786730.jpg

ImageUploadedByStudent Room1473602479.786730.jpg

I get to this, but this isn't the right answer? What step am I missing

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Reply 8

solC

Original post by Eden00

I got rid of the constant the first time I attempted it, the second time I didn't but I'm still running into the same problem.

ImageUploadedByStudent Room1473602479.786730.jpg