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anonymous

  • 5 years ago

discriminant: COMPUTE THE DISCRIMINANT: (d =b^2 -4ac) for the equation: (-1/6x^2) +3x -9 = 0

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  1. anonymous
    • 5 years ago
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    9-4(-1/6)(-9)=9-36/6=9-6=3

  2. anonymous
    • 5 years ago
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    how do you solve can i get the steps :)

  3. anonymous
    • 5 years ago
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    eitaK: Check out the following: http://answers.yahoo.com/question/index?qid=20080304153003AAUaVrd

  4. radar
    • 5 years ago
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    Hey eitaK, I would multiply all terms by -6 to get: \[x ^{2}-18x+54=0\] then the discriminant would be \[-18^{2}-(4)(1)(54)=324-216=108\]

  5. anonymous
    • 5 years ago
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    so technically you are getting rid of the fraction in the first step right?

  6. anonymous
    • 5 years ago
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    and then how did you do the next step?

  7. radar
    • 5 years ago
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    Yesm I believe twhitelsu is also correct. I am sort of confused here.

  8. radar
    • 5 years ago
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    The next step was to square b (-18*-18) then subtract the 4ac or subtract (4*1*54) The results did not equal the same as twhitelsu, and there is nothing wrong with the way it was done to get 3

  9. anonymous
    • 5 years ago
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    ok but what happened to the x's?

  10. radar
    • 5 years ago
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    I would stick the a, b, c, values of the original equation

  11. anonymous
    • 5 years ago
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    ok so that is what i didn't and i go t -18^2- 4(1)(54)

  12. anonymous
    • 5 years ago
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    sorry d= -18 not t.

  13. radar
    • 5 years ago
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    The discriminant only deals with the coefficients of the variable not the variable itself. So there are no x in the discriminant.

  14. anonymous
    • 5 years ago
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    ok

  15. anonymous
    • 5 years ago
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    so then i went further and got-18^2 = -324 and then -4(1)(54) = -216

  16. anonymous
    • 5 years ago
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    so then i woudl have D= -324 -216 correct?

  17. radar
    • 5 years ago
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    Yes, but it doesn't come out as 3, as you would get if you had used the original equation for the values of a, b, c. I thought multiplying thru would simplify it, but it came out with a different discriminant. So apparently multipllying thru by-6 was not the right thing to do. I will think some more about this. I think you are on to the procedure to obtain discriminants.

  18. anonymous
    • 5 years ago
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    i just used the equation that i was given. that i put abvoe :/

  19. radar
    • 5 years ago
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    I just noticed that if I divides the results of 108 by 6 squared (36) it would be 3!!.

  20. anonymous
    • 5 years ago
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    wait but where did you get 108

  21. anonymous
    • 5 years ago
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    you've lost me,

  22. radar
    • 5 years ago
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    The discriminant is that part of the quadratic formula that is within the radical and it is used to the following way: If it is greater than 0, their are two real solutions. If it equals zero there is one real solution (repeated). If it is less than 0, there are no real solutions.

  23. radar
    • 5 years ago
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    The -18 squared results in positive 324 (not the -324) when then combined with the -216 you get the 108 which is positive and means there are 2 real solutions.

  24. anonymous
    • 5 years ago
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    ok... because it it positive?

  25. anonymous
    • 5 years ago
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    and greater than 0 correct?

  26. radar
    • 5 years ago
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    Yes

  27. anonymous
    • 5 years ago
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    ok so then how do i get three as the discriminant?

  28. radar
    • 5 years ago
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    Look at the work at the top of this page provided by twhitelsu.

  29. radar
    • 5 years ago
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    She worked the probllem using the original equation working with the fractional value for a.

  30. anonymous
    • 5 years ago
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    if i am going of yours, which makes a little more sense to me... how did you think and know to do that?

  31. radar
    • 5 years ago
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    Did you follow her steps, see where b (3) was squared to become a 9

  32. anonymous
    • 5 years ago
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    no i don't see where she got the 4 from.

  33. radar
    • 5 years ago
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    I was trying to get rid of the 1/6 (I don't like fractions) lol the result were still positive but was not equal

  34. anonymous
    • 5 years ago
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    i mean looking at hers. i see she has 4

  35. radar
    • 5 years ago
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    the 4 was given in the discriminant equation: b^2-4ac, it is part of the 4ac. get it

  36. radar
    • 5 years ago
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    you can see where she uses the a and c values being that a = -1/6 and c=-9

  37. anonymous
    • 5 years ago
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    oh yes haha thanks.

  38. anonymous
    • 5 years ago
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    but isn't the b supposed to be squared ? so 9^2

  39. radar
    • 5 years ago
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    Look at your equation (-1/6)x^2+3x-9=0 the abc values for your equation are: a=-1/6, b=3, c=-9 So b=3 and b squared if 9

  40. anonymous
    • 5 years ago
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    gotcha! wow haha

  41. anonymous
    • 5 years ago
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    THANKS FOR SPENDING ALL THAT TIME ON THIS PROB!

  42. radar
    • 5 years ago
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    Here is form for a quadratic equation: \[ax ^{2}+bx+c=0\] Note that the abc represents numbers with a and b being the coefficients of variables and c is a constant.

  43. anonymous
    • 5 years ago
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    wait whats that for?

  44. anonymous
    • 5 years ago
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    oh i see.

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