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SUPER QUICK FP1 Maths Question (help)

I have a feeling this is a really obvious one but I can't seem to get it..

(edited 9 years ago)
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Original post by creativebuzz
I have a feeling this is a really obvious one but I can't seem to get it..



Simultaneous equations? :smile:
Original post by usycool1
Simultaneous equations? :smile:


Well I made them equal to each other:

9x=3x

but then the 3x cancels out to give you

3=0

:/
Original post by creativebuzz

but then the 3x cancels out to give you


What do you mean by cancels out?
Original post by creativebuzz
Well I made them equal to each other:

9x=3x

but then the 3x cancels out to give you

3=0

:/


Ah never mind, I see what you've done (divided through by 3x?). If so, instead subtract both sides by 3x so that you get 6x = 0. Then solving for x, you get x = 0.

By dividing though by x (or 3x), you essentially divide through by zero which ruins things. :smile:

(Also, just as an aside, 3x/3x = 1 :tongue:)
It's asking to show that (x, y) is (0, 0) so you can make the equations equal to each other to get 9x=3x.
Then for what value of x would this equation hold?
Next, what value of y do you get when you substitute the newly found value of x into either equation?
Original post by usycool1
Ah never mind, I see what you've done (divided through by 3x?). If so, instead subtract both sides by 3x so that you get 6x = 0. Then solving for x, you get x = 0.

By dividing though by x (or 3x), you essentially divide through by zero which ruins things. :smile:

(Also, just as an aside, 3x/3x = 1 :tongue:)


Omg subtracting, of course! How obvious ariejkhjGH ugh that's so annoying! ahah, thank you so much! :smile:

If you don't mind, could you see where I went wrong in these two questions (sorry about the blurry photos and my messy handwriting) :P


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Original post by creativebuzz
Omg subtracting, of course! How obvious ariejkhjGH ugh that's so annoying! ahah, thank you so much! :smile:

If you don't mind, could you see where I went wrong in these two questions (sorry about the blurry photos and my messy handwriting) :P




For the first one, it looks like what you've done is fine so far. Now just take out a factor of (x+1)−12(x+1)^{-\frac{1}{2}} and play around and you should get it.

For the second one, it looks like you've got the numerator the wrong way round - it should be u'v - uv' whereas you've done uv' - u'v :smile:
Original post by usycool1
For the first one, it looks like what you've done is fine so far. Now just take out a factor of (x+1)−12(x+1)^{-\frac{1}{2}} and play around and you should get it.

For the second one, it looks like you've got the numerator the wrong way round - it should be u'v - uv' whereas you've done uv' - u'v :smile:



As for the first one, I've tried factoring (x+1)^-1/2 out and playing around with the numbers but I still can't seem to get the right answer... :/
Original post by creativebuzz
As for the first one, I've tried factoring (x+1)^-1/2 out and playing around with the numbers but I still can't seem to get the right answer... :/


Post your working? :smile:
Original post by usycool1
Post your working? :smile:


I managed to get question 1 in the end! :biggrin: So thanks! :biggrin:


But as for question 2, I can't seem to get it in the right form...

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Original post by creativebuzz
I managed to get question 1 in the end! :biggrin: So thanks! :biggrin:


But as for question 2, I can't seem to get it in the right form...



Nice. :biggrin:

You've made a mistake when going from the first line to the second. x3(2x)≠6x4x^3(2x) \not= 6x^4 :no:

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