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Math Help - Polynomials and Imaginary numbers

  1. #1
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    Polynomials and Imaginary numbers

    How do I solve questions such as P(x) = 16x^4 - 81


    Am I not allowed to use the Quadratic Formula? Are there any conditions to using the Quadratic Formula? Thanks
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by JonathanEyoon View Post
    How do I solve questions such as P(x) = 16x^4 - 81


    Am I not allowed to use the Quadratic Formula? Are there any conditions to using the Quadratic Formula? Thanks
    Hint: difference of two squares

    and that's just one option, i actually see another way to solve it. you want to find P(x) = 0 right? equate P(x) to 0 and get the x on one side. it's easier than you think, there are no middle terms to bug us
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  3. #3
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    Quote Originally Posted by Jhevon View Post
    Hint: difference of two squares

    and that's just one option, i actually see another way to solve it. you want to find P(x) = 0 right? equate P(x) to 0 and get the x on one side. it's easier than you think, there are no middle terms to bug us


    (4x^2 + 9)(4x^2 - 9)

    May I ask what's the other way
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by JonathanEyoon View Post
    (4x^2 + 9)(4x^2 - 9)
    yes, that's very good! now you notice that what's in the second pair of brackets is also the difference of 2 squares, and what's in the first pair has two imaginary solutions


    May I ask what's the other way
    Nevermind. I tried it, i ended up with something very similar, but i wasn't able to get the imaginary solutions. the above method is best. continue
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  5. #5
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    Quote Originally Posted by Jhevon View Post
    yes, that's very good! now you notice that what's in the second pair of brackets is also the difference of 2 squares, and what's in the first pair has two imaginary solutions


    Nevermind. I tried it, i ended up with something very similar, but i wasn't able to get the imaginary solutions. the above method is best. continue



    Thanks~!!
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