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anonymous

  • one year ago

log(3x+5)-log(x-5)=log(8)

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  1. anonymous
    • one year ago
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    i got it so log(3x+5/x-5)=log8 and dont know where to go from there

  2. Nnesha
    • one year ago
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    hint: \[\huge\rm log_b x = \log_b y\] \[\huge\rm\cancel { log_b} x = \cancel{\log_b} y\] x=y

  3. anonymous
    • one year ago
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    so 3x-5/x-5=8

  4. Nnesha
    • one year ago
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    yep now simple algebra

  5. anonymous
    • one year ago
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    i got -20 but the answer is 9

  6. Nnesha
    • one year ago
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    how did you get -20?

  7. anonymous
    • one year ago
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    i cross multiplied

  8. anonymous
    • one year ago
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    so 8x-40=3x+5

  9. Nnesha
    • one year ago
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    solve for x

  10. anonymous
    • one year ago
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    i got -20

  11. Nnesha
    • one year ago
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    show ur work

  12. anonymous
    • one year ago
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    oh i found my mistake thank you!

  13. Nnesha
    • one year ago
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    r u sure ? u got it ?

  14. anonymous
    • one year ago
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    yep! can i ask you one more though?

  15. Nnesha
    • one year ago
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    alright

  16. anonymous
    • one year ago
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    log8+3logx=3 which i know is log8+logx^3=3 but what do you do if theres no log on the other side?

  17. Nnesha
    • one year ago
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    apply log properties which one you should apply ?

  18. anonymous
    • one year ago
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    change of base?

  19. Nnesha
    • one year ago
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    yeah or convert log to exponential form just like we did before

  20. Nnesha
    • one year ago
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    nope there is a variable so you can't use change of base formula

  21. anonymous
    • one year ago
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    how would you do that though because isnt it 8x^3=3

  22. Nnesha
    • one year ago
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    log (8x^3) = 3

  23. Nnesha
    • one year ago
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    \[\log = \log_{10}\]

  24. anonymous
    • one year ago
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    but idk how you would make that exponential

  25. Nnesha
    • one year ago
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    |dw:1432768266869:dw|

  26. anonymous
    • one year ago
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    but theres no base

  27. Nnesha
    • one year ago
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    there is i just posted that

  28. Nnesha
    • one year ago
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    \[\log = \log_{10}\]

  29. anonymous
    • one year ago
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    oh ok so then i get 10 though and the answe r is 5

  30. Nnesha
    • one year ago
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    xo x = 5 ?

  31. anonymous
    • one year ago
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    10^3=x^3 which is 10

  32. anonymous
    • one year ago
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    oh i forgot the 8

  33. anonymous
    • one year ago
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    oh ok so x=5 got it thanks

  34. Nnesha
    • one year ago
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    yep

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