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anonymous

  • one year ago

Using the following equation, find the center and radius: x2 + 2x + y2 + 4y = 20 The center is located at (1, 2), and the radius is 25. The center is located at (-1, 2), and the radius is 25. The center is located at (-1, -2), and the radius is 5. The center is located at (1, 2), and the radius is 5.

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  1. anonymous
    • one year ago
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    @LynFran

  2. misty1212
    • one year ago
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    HI!!

  3. misty1212
    • one year ago
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    this is a job for "completing the square" you have to do it twice, once for \(x^2+2x\) and again for \(y^2+4y\) it is not too hard do you know how to do it?

  4. anonymous
    • one year ago
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    no

  5. misty1212
    • one year ago
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    ok lets start with \[x^2+2x\] what is half of 2?

  6. anonymous
    • one year ago
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    1

  7. misty1212
    • one year ago
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    right and now what is \(1^2\_?

  8. anonymous
    • one year ago
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    1

  9. misty1212
    • one year ago
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    oops what is \(1^2\)?

  10. misty1212
    • one year ago
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    ok so we turn \[x^2+2x\] in to \[(x+1)^2\] and add 1 to the other side making it \[(x+1)^2+y^2+4y=21\]

  11. misty1212
    • one year ago
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    now repeat with \(y^2+4y\) what is half of 4?

  12. anonymous
    • one year ago
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    2

  13. misty1212
    • one year ago
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    ok and \(2^2\)?

  14. anonymous
    • one year ago
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    2

  15. misty1212
    • one year ago
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    hmm no

  16. anonymous
    • one year ago
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    sorry 4

  17. misty1212
    • one year ago
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    right so turn \(y^2+4y\) in to \((y+2)^2\) and add 4 to the other side

  18. misty1212
    • one year ago
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    now we are at \[(x+1)^2+(y+2)^2=25\] and from that you can read off the center and the radius as it is in standard form for a circle

  19. misty1212
    • one year ago
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    you good from there?

  20. anonymous
    • one year ago
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    Yea so the answer is (-1,-2) radius 5?

  21. misty1212
    • one year ago
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    yes

  22. anonymous
    • one year ago
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    thx

  23. misty1212
    • one year ago
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    \[\color\magenta\heartsuit\]

  24. juanpabloJR
    • one year ago
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    That was great but you can also try-> \(\href{http:///bfy.tw/5Ay}{\sf \huge Click~for~Math~Help}\)

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