logs

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    • #13151

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

      2 2

    • #388

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

      2 2

    • #13152
      Anonymous

      Logarithms

      A logarithm is a way of representing a number by the power of a base.

      i. addition of logs converts to muliplying using this rule

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      clck on image to enlarge

      to view full explanation click here

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

      log (3x^2-5x)=3. multiply out the brackets

      Convert log back to numeric format

      click image to enlarge

      remember: logaM =x means exactly the same thing as saying a^x = M and log means log10 or log to the base power of 10

      becomes

      10^3= (3x^2-5x) multiply out the power

      1000=(3x^2-5x)

      0=3x^2-5x -1000

      use -b+-Sqaure root(b^2-4ac)/2a

      where a is co-efficient of x^2 (the number with the x^2) ie 3

      where b is co-efficient of x (the number with the x]) ie 5

      and c is the number without an x term

      Answer

      x=19.12 and -17.44

      You should learn the 6 rules relating to logs (they come in useful). I'll post a site if I come across one

      Good luck

    • #13153
      Anonymous

      Convert log back to numeric format

      width=150/

    • #13154
      Anonymous

      Properties of Logarithms

      1) width=150/

      width=150/

      Saying that logaM =x means exactly the same thing as saying a^x = M .

      2) width=150/

      the log of the product A*B equals the sum of the logs of A and B

      3) width=150/

      the log of the quotient A/B equals the difference of the logs of A and B.

      4) width=150/

      the log of A to the base a and the power p is equal to p times the log A to the base a

      5) width=150/

      the log of x to the base a is equivilant to the natural log of x divided by the natural log of a. (You would use this rule if you were trying to change the base power)

      visit http://hypatia.math.uri.edu/Courses/spring02/mth111/nancy/prlog1.html

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