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Math Help - Solving a y=x^2 graph

  1. #1
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    Solving a y=x^2 graph

    Hi I have answered some questions and was hoping to find out if I have answered them correctly.

    Questions

    a) Plot on graph paper the graph of y=x^2 for values of x between -8 and +8

    Use the graph to solve the following equations

    b) X^2 = 7x + 2

    c) X^2 = 4 6x

    d) Verify your solutions numerically


    Answers

    Solution to a), b) and c)

    plot x^2 = 7x + 2

    http://www.wolframalpha.com/input/?i=plot+%28y%3Dx^2%29%2C+%28x^2%3D7x%2B2%29+-8+to+8

    and x^2 = 4-6x against y=x^2

    http://www.wolframalpha.com/input/?i=plot+%28y%3Dx^2%29%2C+%28x^2%3D4-6x%29+-8+to+8

    d) Use the quadratic formula to solve numerically

    x^2 = 7x + 2 becomes: x^2-7x-2=0

    x = -0.274197, 7.24792

    x^2 = 4-6x becomes: x^2+6x-4=0

    x= -6.6055551, 0.60555127

    Would simply plotting b) and c) against x^2 be the answer to those questions?

    Thanks for any help.
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  2. #2
    MHF Contributor Siron's Avatar
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    Re: Solving a y=x^2 graph

    In my opinion you didn't answer questions a),b) and c), wolphram alpha did, but I think you understand what to do.
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  3. #3
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    Re: Solving a y=x^2 graph

    lol, it was the easiest way to put a graph up. So simply plotting all 3 graphs against each other would answer the first 3 questions? Sorry, if it is the case I'm just in a little disbelief over it.
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  4. #4
    MHF Contributor Siron's Avatar
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    Re: Solving a y=x^2 graph

    Yes, in my opinion the first question is a little bit strange, you have to use both graphs to solve it graphically, if you want to determine x^2=7x+2 then plot the graphs y=x^2 and y=7x+2 and look where they have intersection points.
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  5. #5
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    Re: Solving a y=x^2 graph

    Thank you!
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