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anonymous

  • 4 years ago

im lost ... −16t2+80x−60=0 Solving for t, t=(5±10−−√)2

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  1. lgbasallote
    • 4 years ago
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    why do you have mixed variables -__-

  2. campbell_st
    • 4 years ago
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    well simplify the problem -4(4t^2 - 20t +15)

  3. anonymous
    • 4 years ago
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    Ah this is the a nswer i gave you earlier for the height?

  4. anonymous
    • 4 years ago
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    yeah im lost

  5. campbell_st
    • 4 years ago
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    so using the GQF \[t = (20\pm \sqrt{(-20)^2-4\times4\times15})/(2 \times4)\] \[t = (20 \pm \sqrt{16 \times10})/8 = (5\pm \sqrt{10})/2\]

  6. anonymous
    • 4 years ago
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    umm yeah im already there

  7. anonymous
    • 4 years ago
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    Screw it the equation th ing is broken

  8. anonymous
    • 4 years ago
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    Use the quadratic formula to s olve for t

  9. anonymous
    • 4 years ago
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    \[t=\frac{-b \pm \sqrt{b^2-4ac}}{2a}\]

  10. anonymous
    • 4 years ago
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    I dont think ive learned that yet

  11. anonymous
    • 4 years ago
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    in my class

  12. anonymous
    • 4 years ago
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    Is this a physics problem or calculus?

  13. anonymous
    • 4 years ago
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    calculus

  14. anonymous
    • 4 years ago
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    You should've learned the quadratic formula back in algebra

  15. anonymous
    • 4 years ago
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    woops....

  16. anonymous
    • 4 years ago
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    lol

  17. anonymous
    • 4 years ago
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    so i would just plug in the numbers that were found in the early part of the question?

  18. anonymous
    • 4 years ago
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    \[ax^2+bx+c=0\], you can only use the quadratic formula when you have your equation like this

  19. anonymous
    • 4 years ago
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    in this case you do, and you can also divide out a 4 from all the terms 16,80, and 60

  20. anonymous
    • 4 years ago
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    \[-4t^2+20x-15=0\] a=-4 b=20 c=-15

  21. anonymous
    • 4 years ago
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    ok? so now I can solve by getting

  22. anonymous
    • 4 years ago
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    by itself

  23. anonymous
    • 4 years ago
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    T

  24. anonymous
    • 4 years ago
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    no, use the quadratic formula as it is written above right now, \[t=\frac{-b \pm \sqrt{b^2-4ac}}{2a}\]

  25. anonymous
    • 4 years ago
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    \[t=\frac{-20 \pm \sqrt{20^2-4(-4)(-15)}}{2(-4)}\]

  26. anonymous
    • 4 years ago
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    \[t=\frac{-20 \pm \sqrt{160}}{-8}=\frac{-20 \pm 4\sqrt{10}}{-8}=\frac{-5 \pm \sqrt{10}}{-2}=\frac{5 \pm \sqrt{10}}{2}\]

  27. anonymous
    • 4 years ago
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    t= -20 sqrt 360/-8

  28. anonymous
    • 4 years ago
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    look above

  29. anonymous
    • 4 years ago
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    wow im way off!!

  30. anonymous
    • 4 years ago
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    Remember to keep the positive and negative signs for a,b,c

  31. anonymous
    • 4 years ago
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    so now I have 3.16227766/2 = 1.58113883

  32. anonymous
    • 4 years ago
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    5+ or - = 1.58113883

  33. anonymous
    • 4 years ago
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    \[t \approx .9189s, t \approx 4.081s\]

  34. anonymous
    • 4 years ago
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    can you give me the all the numbers shown on your calculator

  35. anonymous
    • 4 years ago
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    They are irrational numbers, there are infinitely many decimal places

  36. anonymous
    • 4 years ago
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    Use the answer with the square root

  37. anonymous
    • 4 years ago
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    That is accurate

  38. anonymous
    • 4 years ago
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    no just the numbers shown on your calculator bcause I need the precise number

  39. anonymous
    • 4 years ago
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    You can't get a precise number from an irrational number! Use \[t=\frac{5 \pm \sqrt{10}}{2} s\]

  40. anonymous
    • 4 years ago
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    That is the precise answer, any decimal answer is an approximation

  41. anonymous
    • 4 years ago
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    what I mean is when plug the answers into the my computer it needs the closets thing to an approximate number

  42. anonymous
    • 4 years ago
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    so it must have the all the numbers shown from the calculator for it to be correct

  43. anonymous
    • 4 years ago
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    Your calculator can show hundreds of digits if you want it to

  44. anonymous
    • 4 years ago
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    How many decimal places do you need?

  45. anonymous
    • 4 years ago
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    \[t \approx 0.918861169916s, t \approx 4.08113883008s\]

  46. anonymous
    • 4 years ago
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    like im using a standard calcultor so it only shows like 9 or 10 numbers

  47. anonymous
    • 4 years ago
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    here are my instructions : For example, the fraction 2/3 is exact, while the decimals 0.67, 0.666666667 and 0.666666666666666666667 are all approximate values for 2/3. Where an exact answer is called for, an approximate answer will be marked wrong.

  48. anonymous
    • 4 years ago
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    So if you use a decimal here, you will be wrong

  49. anonymous
    • 4 years ago
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    yup lol

  50. anonymous
    • 4 years ago
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    Use the answer i gave you with the square root

  51. anonymous
    • 4 years ago
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    so like t t= .9189 just sqrt it

  52. anonymous
    • 4 years ago
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    ...

  53. anonymous
    • 4 years ago
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    \[t=\frac{5+\sqrt{10}}{2}, t=\frac{5-\sqrt{10}}{2}\]

  54. anonymous
    • 4 years ago
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    Those are the exact answers for the time

  55. anonymous
    • 4 years ago
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    ok got it , thanks sorry for the confusion !!

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