Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

donovan11

  • 3 years ago

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

  • This Question is Closed
  1. donovan11
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    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

  2. amistre64
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ln(a) + ln(b) = ln(ab)

  3. donovan11
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    That's x^2+x-20?

  4. amistre64
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yep. now, ln(0) = 1 because e^0 = 1

  5. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    and also any number to the 0 power except 0 is 1

  6. amistre64
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    your equation is really: x^2 +x - 20 = 0

  7. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    wait!

  8. amistre64
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    or (x-4) (x+5) = 0

  9. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    e^1=e

  10. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    we have (x-4)(x+5)=e

  11. amistre64
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    lol..... maybe it does, and maybe it doesnt :)

  12. beens
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes myininaya

  13. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    if we do it like amistre we would make the problem much easier but also kindof wrong

  14. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    and kindof wrong is just wrong

  15. donovan11
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    now im confused >_<

  16. amistre64
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    horseshoe and handgranades me friend :)

  17. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so we have x^2-9x+20+e=0

  18. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oops -e

  19. donovan11
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    wouldnt it be -e?

  20. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yes i blame amistre

  21. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    lol

  22. beens
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    bring over 1 to the left at the start...before changinglg form...

  23. amistre64
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ...its my liver pills...blame the liver pills :)

  24. donovan11
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so whats the answer?

  25. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    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)

  26. beens
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    sorry...doesn't make a difference what I said

  27. beens
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Quadratic formula the way to go

  28. donovan11
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    this is what i put on the formula -1+squareroot(1^2 -4(1)(20-e))))/2

  29. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    no

  30. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    a=1 n=-9 c=20-e correct?

  31. beens
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    c=-20-e

  32. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    b=-9*

  33. beens
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    b=1

  34. donovan11
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    no b =1

  35. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    dont listen to me

  36. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    im doing two things at once sorry

  37. donovan11
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    my calculator wont work

  38. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    (-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

  39. amistre64
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    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.

  40. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    correct!

  41. myininaya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    that negative number gives you another negative number when you plug it into x-4

  42. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.