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cutiecomittee123

  • one year ago

x^2+4y=100 4y-x^2=-20 How in the world so I solve this system of equations please help fast! Do I use substitution? I don't clearly see how I would solve for x or y in either equation.

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  1. anonymous
    • one year ago
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    you can use substitution because x^2 on the first equation is positive and negative on the second equation. They will cancel out

  2. anonymous
    • one year ago
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    *as i was, the 4y's will cancel out

  3. cutiecomittee123
    • one year ago
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    so add them together

  4. cutiecomittee123
    • one year ago
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    I get y=10

  5. anonymous
    • one year ago
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    yup x^2-(-x^2)=2x^2 and then 100-(-20)=120 2x^2=120 120/2=60 x^2=60 and then take the square root

  6. cutiecomittee123
    • one year ago
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    yeah so square root of 60 = x

  7. anonymous
    • one year ago
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    exactly, and whatever x equals you plug it into to one of the equations to find y

  8. cutiecomittee123
    • one year ago
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    I plugged it into the second equation and it worked. So does that mean there is only one solution?

  9. anonymous
    • one year ago
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    no the number you plugged in is the answer for x. The answer you got after you plugged it in is y

  10. anonymous
    • one year ago
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    remember, there is an x and a y so there has to be at least 2 answers, one for each letter

  11. cutiecomittee123
    • one year ago
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    Yeah so (sqrt60, 10) is the only solution?

  12. cutiecomittee123
    • one year ago
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    I got the answer wrong it was actually (6,4) :(((

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