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anonymous

  • 5 years ago

A circle is defined by the following equation: 3x^(2)+3y^(2)+30x+30y+150=0 What is its radius?

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  1. amistre64
    • 5 years ago
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    divide all by 3 (x^2 +10x) + (y^2 +10y) = -50

  2. amistre64
    • 5 years ago
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    now complete the squares of the x and y (x^2 +10x +25) + (y^2 +10y +25) = -50-25-25 (x+5)^2 +(y+5)^2 = -100 are you sure it aint -150?

  3. amistre64
    • 5 years ago
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    teh radius is most likely 10

  4. amistre64
    • 5 years ago
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    or 0 lol

  5. anonymous
    • 5 years ago
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    no, in the original equation, all numbers are positive.

  6. amistre64
    • 5 years ago
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    -50+25+25=0 then

  7. amistre64
    • 5 years ago
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    looks to be 0 for some reason

  8. amistre64
    • 5 years ago
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    i gotta wonder, is 0 correct?

  9. anonymous
    • 5 years ago
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    When dividing by 3, (x^(2)+10x)+(y^(2)+10y)=-50, how do you get 10x and 10y?

  10. amistre64
    • 5 years ago
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    3(x^2 +10x+25)-75 +3(y^2 +10y+25)-75= -150 3(x^2 +10x+25) +3(y^2 +10y+25)= -150 +75+75 = 0

  11. amistre64
    • 5 years ago
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    3*10 = 30 right?

  12. anonymous
    • 5 years ago
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    I dont understand how you get rid of the x and y

  13. amistre64
    • 5 years ago
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    i dint get rid of anything :) i moved them around to work with them easier, thats all

  14. anonymous
    • 5 years ago
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    but if there's a variable on the left side of the equation, shouldnt there still be a variable on the right side?

  15. anonymous
    • 5 years ago
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    Actually, shouldn't it remain -50-25-25, and not -50+25+25?

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