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anonymous

  • one year ago

what are the values of x in this equation? x^(2/5)+x^(1/5)+1=3 answers: 32,-1 32,1 -32,1 -32,-1

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  1. Theloshua
    • one year ago
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    ummmm okay, so the first thing your gonna do is subtract one from both sides

  2. anonymous
    • one year ago
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    Subtract 3 from both sides, because then one side will be 0 and you can factor or use the quadratic equation

  3. Theloshua
    • one year ago
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    \[x ^{\left(\begin{matrix}2 \5\ ?\end{matrix}\right)} + x ^{\left(\begin{matrix}1 \5 \ ?\end{matrix}\right)}=3\]

  4. Theloshua
    • one year ago
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    is that the equation?

  5. anonymous
    • one year ago
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    the equation is x^(2/5)+x^(1/5)+1=3

  6. anonymous
    • one year ago
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    how do i subtract 3 from the left side? do i plug in the numbers first?

  7. anonymous
    • one year ago
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    x^(2/5) + x^(1/5) + 1 = 3 x^(2/5) + x^(1/5) - 2 = 0

  8. Theloshua
    • one year ago
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    oh wait, your right :D do your thing XD

  9. anonymous
    • one year ago
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    you can do a change of variables. Let u = x^(1/5), then the equation becomes u² + u - 2 = 0 Solve the quadratic equation for u Then go back and solve for x

  10. anonymous
    • one year ago
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    so its 32 and 1 that equals 3 right?

  11. anonymous
    • one year ago
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    32^2/5+1^1/5-2=0

  12. anonymous
    • one year ago
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    no it doesn't work that way. The solutions have to work individually. You can't mix them. Factor the quadratic equation I put above to get solutions for u

  13. anonymous
    • one year ago
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    hello

  14. anonymous
    • one year ago
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    u^2+u=2 u(u+1)=2 u=1

  15. anonymous
    • one year ago
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    how to i solve for x? x^(1/5)=1? is that how i do it?

  16. anonymous
    • one year ago
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    if that is the value of u, then yes, there should be 2 values for u though

  17. anonymous
    • one year ago
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    how do I get two values for u then?

  18. anonymous
    • one year ago
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  19. anonymous
    • one year ago
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    they aren't using the same kind of numbers i am. what am i doing wrong?

  20. anonymous
    • one year ago
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    Refer to the attachment from Mathematica 9.

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  21. anonymous
    • one year ago
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    @robtobey how does that help me?

  22. anonymous
    • one year ago
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    It provides the right answer.

  23. anonymous
    • one year ago
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    you didn't factor that right. the video @billj5 posted shows you how to factor. @robtobey gave you the answer

  24. anonymous
    • one year ago
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    where is the answer in it?

  25. anonymous
    • one year ago
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    none of your options are going to work because 1 is the only solution to this equation.

  26. anonymous
    • one year ago
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    that's what i thought but it doesn't give me an option for just 1.

  27. anonymous
    • one year ago
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    ok. let's see if we can find another Factor this u² + u - 2 = 0 What 2 numbers multiply to -2 and add to 1?

  28. anonymous
    • one year ago
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    1?

  29. anonymous
    • one year ago
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    Quadratic equations have 2 solutions, so we need TWO numbers. Look at the factors of -2 and then figure out which pair adds to 1.

  30. anonymous
    • one year ago
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    ?

  31. anonymous
    • one year ago
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    i still don't understand any of this. :(

  32. anonymous
    • one year ago
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    i figured it out!!

  33. anonymous
    • one year ago
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    ok. What did you get?

  34. anonymous
    • one year ago
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    -32,1

  35. anonymous
    • one year ago
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    yeah that's right :)

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