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    I can do (a) and I can do most of (b)- I can get the distances of P to A (PA) and P to B (PB) but then I don't know what to do with them to show PB=2PA??? Thanks!
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    (Original post by rpnom)
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    I can do (a) and I can do most of (b)- I can get the distances of P to A (PA) and P to B (PB) but then I don't know what to do with them to show PB=2PA??? Thanks!
    Well, if you know PA and PB then you just need to say that the first is twice the second? Can we see your working out?
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    (Original post by Zacken)
    Well, if you know PA and PB then you just need to say that the first is twice the second? Can we see your working out?
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    (Original post by rpnom)
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    You've said A is the point \left(\frac{3}{2p}, 0\right) and B is the point (0, 3p^2). I agree with this.

    Now the point P is \left(\frac{1}{p}, p^2\right). Can you now find the correct distances PA and PB using the standard distance formula?
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    (Original post by Zacken)
    You've said A is the point \left(\frac{3}{2p}, 0\right) and B is the point (0, 3p^2). I agree with this.

    Now the point P is \left(\frac{1}{p}, p^2\right). Can you now find the correct distances PA and PB using the standard distance formula?
    I sort of did that didn't I? I found PA^2 and PB^2 using that formula? :/
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    (Original post by rpnom)
    I sort of did that didn't I? I found PA^2 and PB^2 using that formula? :/
    Look at your PA^2, why are you subtracting 0 from both of them?

    It should be PA^2 = \left(\frac{3}{2p} - \frac{1}{p}, 0 - \frac{1}{p^2}\right) and same for PB - you seem to be treating P as (0,0).
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    (Original post by rpnom)
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    Despite the fact you subtracted 0 twice (as Zacken pointed out), you got the correct distances. Now pull out a factor of 4 in your PB^{2} = \frac{1}{p^{2}}+4p^{4} and you should find that you get  PB^{2} = 4PA^{2}
 
 
 
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