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Homework Help: 2 Questions

  1. Oct 14, 2004 #1
    A Question

    1. If x^2 + y^2 = 16 and xy = 8 then what is (x+y)^2 ?

    32, correct?

    90?
    120?
    1260?
    150?
     
    Last edited: Oct 14, 2004
  2. jcsd
  3. Oct 14, 2004 #2

    arildno

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    1. Incorrect; think again.
     
  4. Oct 14, 2004 #3
    I meant to put 32, whoops.
     
  5. Oct 14, 2004 #4

    arildno

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    Still incorrect..
     
  6. Oct 14, 2004 #5
    (x+y)^2 = x^2 +2xy + y^2

    xy = 8
    x^2 + y^2 = 16

    2(8) = 16 + 16 = 32

    Where am I going wrong?
     
  7. Oct 14, 2004 #6

    arildno

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    Well, from your first post, it says xy=18..
     
  8. Oct 14, 2004 #7
    Ah, thanks.
     
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