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anonymous

  • 5 years ago

Use the substitution method to solve x^2+2y^2=9 x-y+3=0 can someone show me the steps?

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  1. anonymous
    • 5 years ago
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    I have already solved this before. You've asked the same question lol, search for the old one ^_^

  2. anonymous
    • 5 years ago
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    oh wait, it's different ^^" my bad.

  3. anonymous
    • 5 years ago
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    yea the y^2 is throwing me off.

  4. anonymous
    • 5 years ago
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    i came up w/ x=(-1,-3) y=(2,0) but im not sure thats right...

  5. anonymous
    • 5 years ago
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    Alright, first of all, call your equations as (a) and (b). Now, let's re-write equation (b) in terms of y and we'll get: y = 3 + x Substitute this equation in (a) and you'll get: \[x^2 + 2(3+x)^2 - 9 = 0\] \[x^2 + 2(3+x)(3+x) -9 =0\] \[x^2 + 2x^2 + 12x + 18 -9 = 0\] \[3x^2 + 12x -9 = 0\] \[(3x-3)(x-9) = 0\] so x = 1 and x =3 Plug these 2 x's in equation b and find the 2 points ^_^ give it a try now :)

  6. anonymous
    • 5 years ago
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    k

  7. anonymous
    • 5 years ago
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    Your points should be (1,4) and (3, 6) :)

  8. anonymous
    • 5 years ago
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    DOn't you mean x = 1 and x = 9

  9. anonymous
    • 5 years ago
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    lol right right! >_< thank you :)

  10. anonymous
    • 5 years ago
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    wait no!

  11. anonymous
    • 5 years ago
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    oh dear , I messed up again the equation should be: (3x-3)(x-3) = 0 instead of (x-9)

  12. anonymous
    • 5 years ago
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    so you have x = 1 and x = 3 ^^" sorry lol

  13. anonymous
    • 5 years ago
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    plug these in equation (b) and you'll get (1,4) and (3,6) as your points :)

  14. anonymous
    • 5 years ago
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    and thank you blexting :)

  15. anonymous
    • 5 years ago
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    it wouldnt be (1,4) and (3,12)?

  16. anonymous
    • 5 years ago
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    no ,it'll be (1,4 ) and (3,6) I made a silly mistake in the previous last line where I have put: (3x -3)(x-9) = 0 it should be : (3x -3)(x-3) = 0 instead :)

  17. anonymous
    • 5 years ago
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    plug x = 3 in the equation and you'll get the other point (3,6) ^_^

  18. anonymous
    • 5 years ago
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    ok I see. that x-9 was throwing me off. Thans for your help!

  19. anonymous
    • 5 years ago
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    np :) again, sorry for the mess ^^"

  20. anonymous
    • 5 years ago
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    Wait. x^2+2x+12+18-9=0 wouldnt this simplify to 3x^2+2x+9=0 ?

  21. anonymous
    • 5 years ago
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    you have negative 9

  22. anonymous
    • 5 years ago
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    oh right! >_< again sorry lol

  23. anonymous
    • 5 years ago
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    yo'll have negative 3 and not 9

  24. anonymous
    • 5 years ago
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    Ok I think i have it.

  25. anonymous
    • 5 years ago
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    awesome! :)

  26. anonymous
    • 5 years ago
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    awesome indeed

  27. anonymous
    • 5 years ago
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    :)

  28. anonymous
    • 5 years ago
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    when i solve I keep coming up with x=(-1,-3) y=(2,0)?

  29. anonymous
    • 5 years ago
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    y=2 and x=1

  30. anonymous
    • 5 years ago
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    or y=0 and x=3

  31. anonymous
    • 5 years ago
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    yes! excellent js! :)

  32. anonymous
    • 5 years ago
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    I'll give you a star ^_^

  33. anonymous
    • 5 years ago
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    truly excellent...

  34. anonymous
    • 5 years ago
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    a star from me too

  35. anonymous
    • 5 years ago
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    lol ^_^

  36. anonymous
    • 5 years ago
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    i mean y=0 and x=-3

  37. anonymous
    • 5 years ago
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    lol abigail :)

  38. anonymous
    • 5 years ago
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    i know what you mean, dont wory

  39. anonymous
    • 5 years ago
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    thank you for your support too ^_^

  40. anonymous
    • 5 years ago
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    you know what I mean?

  41. anonymous
    • 5 years ago
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    i know what i know

  42. anonymous
    • 5 years ago
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    so, what did I mean?

  43. anonymous
    • 5 years ago
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    I know what you know I know

  44. anonymous
    • 5 years ago
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    ._. ...now I don't even know what I have said

  45. anonymous
    • 5 years ago
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    i know you dont know what you think you dont know

  46. anonymous
    • 5 years ago
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    I don't even know what I know now x_x

  47. anonymous
    • 5 years ago
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    LOL, stop my head is spinning! @_@

  48. anonymous
    • 5 years ago
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    Well guys i know i appreciate the help:)

  49. anonymous
    • 5 years ago
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    np js :)

  50. anonymous
    • 5 years ago
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    i know it is

  51. anonymous
    • 5 years ago
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    I don't even know what is what right now, but I do know that the word "know" sounds funny nowx_x

  52. anonymous
    • 5 years ago
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    just say "know" 29 times out loud, and then pause for 5 sec, and say it again, and i promisse, it will sound weird

  53. anonymous
    • 5 years ago
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    LOL

  54. anonymous
    • 5 years ago
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    go finish your 5 $ work =P

  55. anonymous
    • 5 years ago
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    finished all the orders already

  56. anonymous
    • 5 years ago
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    made a fortune

  57. anonymous
    • 5 years ago
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    atleast you had fun :)

  58. radar
    • 5 years ago
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    This solution was very difficult to follow. I hope js14 understands the final answer is x=-3, y=0

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