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donovan11 Group Title

Solve the logarithmic equation for . Please round the answer to four decimal places, if necessary. ln(x-4)+ln(x+5)=1

  • 3 years ago
  • 3 years ago

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  1. donovan11 Group Title
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    Reason I'm confused is because unlike log, in ln the exponential form is e^y=x and I'm having trouble solving the rest

    • 3 years ago
  2. amistre64 Group Title
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    ln(a) + ln(b) = ln(ab)

    • 3 years ago
  3. donovan11 Group Title
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    That's x^2+x-20?

    • 3 years ago
  4. amistre64 Group Title
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    yep. now, ln(0) = 1 because e^0 = 1

    • 3 years ago
  5. myininaya Group Title
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    and also any number to the 0 power except 0 is 1

    • 3 years ago
  6. amistre64 Group Title
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    your equation is really: x^2 +x - 20 = 0

    • 3 years ago
  7. myininaya Group Title
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    wait!

    • 3 years ago
  8. amistre64 Group Title
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    or (x-4) (x+5) = 0

    • 3 years ago
  9. myininaya Group Title
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    e^1=e

    • 3 years ago
  10. myininaya Group Title
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    we have (x-4)(x+5)=e

    • 3 years ago
  11. amistre64 Group Title
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    lol..... maybe it does, and maybe it doesnt :)

    • 3 years ago
  12. beens Group Title
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    yes myininaya

    • 3 years ago
  13. myininaya Group Title
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    if we do it like amistre we would make the problem much easier but also kindof wrong

    • 3 years ago
  14. myininaya Group Title
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    and kindof wrong is just wrong

    • 3 years ago
  15. donovan11 Group Title
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    now im confused >_<

    • 3 years ago
  16. amistre64 Group Title
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    horseshoe and handgranades me friend :)

    • 3 years ago
  17. myininaya Group Title
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    so we have x^2-9x+20+e=0

    • 3 years ago
  18. myininaya Group Title
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    oops -e

    • 3 years ago
  19. donovan11 Group Title
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    wouldnt it be -e?

    • 3 years ago
  20. myininaya Group Title
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    Yes i blame amistre

    • 3 years ago
  21. myininaya Group Title
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    lol

    • 3 years ago
  22. beens Group Title
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    bring over 1 to the left at the start...before changinglg form...

    • 3 years ago
  23. amistre64 Group Title
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    ...its my liver pills...blame the liver pills :)

    • 3 years ago
  24. donovan11 Group Title
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    so whats the answer?

    • 3 years ago
  25. myininaya Group Title
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    use quadractic formula x=(9@sqrt(81-4(1)(20-e))/2 where @ means + or -, but make sure your answer is positive because you cannot do ln(negative)

    • 3 years ago
  26. beens Group Title
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    sorry...doesn't make a difference what I said

    • 3 years ago
  27. beens Group Title
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    Quadratic formula the way to go

    • 3 years ago
  28. donovan11 Group Title
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    this is what i put on the formula -1+squareroot(1^2 -4(1)(20-e))))/2

    • 3 years ago
  29. myininaya Group Title
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    no

    • 3 years ago
  30. myininaya Group Title
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    a=1 n=-9 c=20-e correct?

    • 3 years ago
  31. beens Group Title
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    c=-20-e

    • 3 years ago
  32. myininaya Group Title
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    b=-9*

    • 3 years ago
  33. beens Group Title
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    b=1

    • 3 years ago
  34. donovan11 Group Title
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    no b =1

    • 3 years ago
  35. myininaya Group Title
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    dont listen to me

    • 3 years ago
  36. myininaya Group Title
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    im doing two things at once sorry

    • 3 years ago
  37. donovan11 Group Title
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    my calculator wont work

    • 3 years ago
  38. myininaya Group Title
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    (-1+sqrt(1-4(-20-e))/2=4.2925 and (-1-sqrt(1-4(-20-e))/2=-5.2925 but we can't use -5.2925 since it is negative and the natural log of a negative number doesnt exist

    • 3 years ago
  39. amistre64 Group Title
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    x can be negative if it is not the only thing controling the value of the log. the thing is: x-4 needs to be greater than 0 and, x+5 needs to be greater than 0. x >4 serves both cases.

    • 3 years ago
  40. myininaya Group Title
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    correct!

    • 3 years ago
  41. myininaya Group Title
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    that negative number gives you another negative number when you plug it into x-4

    • 3 years ago
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