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# How to show that x = y ?? (2,3 marks) Watch

1. (Original post by CharlieBoardman)
You needed to square it so that it could be turned into a quadratic equation when you subbed in your y^2=x^2-4.

EDIT: The question doesn't tell you to square both sides, you just have to see that it has to be done, in order to turn in into a quadratic
Ok so every time a question asks me to turn something into a quadratic, I must remember to square both sides.

Then rearrange to get a quad equation

then just do the forumla to get the answer
2. (Original post by blueray)
Ok so every time a question asks me to turn something into a quadratic, I must remember to square both sides.

Then rearrange to get a quad equation

then just do the forumla to get the answer
Not necessarily. In some cases, you may be able to rearrange a given formula into a quadratic without squaring both sides. It was just that in this case, that is what you had to do.

We knew that we had 2.1y=.....
And we had an equation from before which was y^2=x^2-4.
So you should be able to see that by squaring the 2.1y, and then subbing in the x^2-4 for your y^2, you can change it into a quadratic you needed to square so you ended up with a y^2 somewhere, so that you could sub
3. (Original post by CharlieBoardman)
Not necessarily. In some cases, you may be able to rearrange a given formula into a quadratic without squaring both sides. It was just that in this case, that is what you had to do.

We knew that we had 2.1y=.....
And we had an equation from before which was y^2=x^2-4.
So you should be able to see that by squaring the 2.1y, and then subbing in the x^2-4 for your y^2, you can change it into a quadratic you needed to square so you ended up with a y^2 somewhere, so that you could sub
Ok so it's based on the first part.
4. (Original post by blueray)
I have done part i) And have the correct answer of
Pos a
x^2=y^2+4

Pos b

(x+0.95)^2 = (y+1.05)^2 + 4

Edit (thanks guys)

I don't know how to do the LAST part, and would be grateful, if you could go through it

Thank you!

Question bellow.

Attachment 146020
Is this for the new Edexcel maths specification? If so, where did you get these questions? 7 marks O_o.
5. (Original post by blueray)
Ok so it's based on the first part.
Yes

(Original post by InvertedLayman)
Is this for the new Edexcel maths specification? If so, where did you get these questions? 7 marks O_o.
6. (Original post by CharlieBoardman)
Yes

*Sigh of relief*

Wow I could actually do this though, fun times.
7. (Original post by CharlieBoardman)
Not necessarily. In some cases, you may be able to rearrange a given formula into a quadratic without squaring both sides. It was just that in this case, that is what you had to do.

We knew that we had 2.1y=.....
And we had an equation from before which was y^2=x^2-4.
So you should be able to see that by squaring the 2.1y, and then subbing in the x^2-4 for your y^2, you can change it into a quadratic you needed to square so you ended up with a y^2 somewhere, so that you could sub
Btw the answers don't say don't say anything about the other negative x and y?? Only the postive ones? This is because you can't have negative numbers in pythagoras.
8. (Original post by InvertedLayman)
*Sigh of relief*

Wow I could actually do this though, fun times.
Yes, it's good stuff. This question only requis you to use concepts that are GCSE Level though. We also learn calculus and advanced trig etc. Basically most of the stuff in C1 and C2 of A-Level Maths.
9. (Original post by blueray)
Btw the answers don't say don't say anything about the other negative x and y?? Only the postive ones? This is because you can't have negative numbers in pythagoras.
Percisely, you can't have a negative length can you
10. (Original post by CharlieBoardman)
Yes, it's good stuff. This question only requis you to use concepts that are GCSE Level though. We also learn calculus and advanced trig etc. Basically most of the stuff in C1 and C2 of A-Level Maths.
Calculus, yes is not in GCSE. The basic A level Trig. can be done with sound knowledge of GCSE Trig. so I assume Trig. in FSMQ would be well within reach.
11. (Original post by InvertedLayman)
Calculus, yes is not in GCSE. The basic A level Trig. can be done with sound knowledge of GCSE Trig. so I assume Trig. in FSMQ would be well within reach.
Well yes, they were just a couple of examples though. I don't think it would be possible to do binomial distributions with GCSE knowledge. And when I referred to advanced trig, I didn't mean simply to Sine and Cosine rules. I meant trigonomical equations, for which you would need to know a few rules to figure out, e.g. or
You would be given an equation for which you would need to know these rules to figure out

Updated: May 6, 2012
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