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Math Help - Ti-89: Solving Radicals?

  1. #1
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    Ti-89: Solving Radicals?

    How would I enter √8x^5 to output 2x^2√2x or another problem is (index 3)√81x^10 to output 3x^3 (index 3)√3x ? Thanks for the help.
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  2. #2
    MHF Contributor Mathstud28's Avatar
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    Quote Originally Posted by riker View Post
    How would I enter √8x^5 to output 2x^2√2x or another problem is (index 3)√81x^10 to output 3x^3 (index 3)√3x ? Thanks for the help.
    expand(\sqrt{8x^5})

    its under F2
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  3. #3
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    Thank you for your response. Well, itíll only accept it as expand(√(8x^5)) and the output is then 2^3/2√x^5 instead of the answer in my lecture notes. Also, I still donít know how to enter an index number on the calculator for a radical.
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  4. #4
    Moo
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    Hello,

    What do you mean by "index number" ?
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  5. #5
    MHF Contributor Mathstud28's Avatar
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    Quote Originally Posted by riker View Post
    How would I enter √8x^5 to output 2x^2√2x or another problem is (index 3)√81x^10 to output 3x^3 (index 3)√3x ? Thanks for the help.
    use your algebra rules to rewrite \sqrt[3]{3x}=(3x)^{\frac{1}{3}}

    which is easily imputtable into our calculator
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  6. #6
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    Isn't index (n) the small number inside what looks to be a check √ in a square root?

    Quote Originally Posted by Mathstud28 View Post
    use your algebra rules to rewrite \sqrt[3]{3x}=(3x)^{\frac{1}{3}}

    which is easily imputtable into our calculator
    My input = expand((81x^10)^(1/3))

    Output = 3^(4/3)*x^(10/3)

    What's going on?
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  7. #7
    Moo
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    Yep (I didn't understand at first time), but \sqrt[n]{x}=x^{\frac 1n}
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  8. #8
    MHF Contributor Mathstud28's Avatar
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    Quote Originally Posted by riker View Post
    Isn't index (n) the small number inside what looks to be a check √ in a square root?
    Yes...it is...But Moo is from france and she might not have heard that expression I am sure she knows what it means but in a different form..look at my above post for your asnwer
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  9. #9
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    I edited my post. If you would, could to take a look at where I went wrong?
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  10. #10
    Moo
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    Well this is the right thing...
    Though I'm not sure your calculator will give you exactly what you want :

    3x^3 (index 3)√3x
    Calculator has to be a tool, not a solver
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  11. #11
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    Quote Originally Posted by Moo View Post
    Well this is the right thing...
    Though I'm not sure your calculator will give you exactly what you want :

    Calculator has to be a tool, not a solver
    The calculator is clearly solving but it is displaying one of two possible outputs for radicals. You said so yourself that you're not sure whether both can be displayed using certain methods or not. Now, the question becomes is there a way to get √8x^5 to output as 2x^2√2x on a Ti-89 calculator?
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