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I need some help in these two Questions

  1. Oct 3, 2009 #1


    Hi every body , I had alot of equations to solve yesterday

    becouse that i was preparing my self for my exam this sunday

    and i've did .. but these TWO equations .. i couldn't be sure about my results

    can you help me to solve them ..

    1- The variables p and q are related by the law q=ap^b , where a and b are constants . Given that ln(p) = 1.32 when ln(q)= 1.73 and ln(p)=0.44 when ln(q)=1.95 ,
    find the values of a and b .

    2- Write logb (x) + n as one logarithm​

    * b is the base

     
    Last edited: Oct 3, 2009
  2. jcsd
  3. Oct 3, 2009 #2

    tiny-tim

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    Welcome to PF!

    Hi RaYaMe! Welcome to PF! :smile:

    (try using the X2 tag just above the Reply box :wink:)

    Show us what you got, and then we'll know how to help! :smile:
     
  4. Oct 4, 2009 #3
    for the second one ..
    2- Write logb (x) + n as one logarithm

    i've tried =>

    logb (x) + logb (b)^n = logb (X.b^n) ?? or it's canceled

    :biggrin:

    AND ..the first one .. i tried to take ln of both sides ( q=ap^b)

    lnq = lna + b lnp

    It'll be >> 1- 1.73= lna + 1.32 b

    >> 2- 1.95 = lna + 0.44 b

    that's what i've did to get the value of " b "

    1.73=lna + 1.32 b
    -1.95 = -lna - 0.44 b
    ___________________
    -0.22 = 0.88 b >>>>> b= -0.22/0.88 = -0.25

    1.73 = lna + ( 1.32 * -0.25 )
    1.73 + 0.33 = lna
    2.06 = lna

    so , a = e^2.06 :biggrin: what do you think about my ways ..
     
    Last edited: Oct 4, 2009
  5. Oct 4, 2009 #4

    tiny-tim

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    Yes, that looks fine! :smile:
     
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