A Maths (logarithm) question help.

• Lohhwee

  12 Jun 12, 22:39

  Hi . 

  How to solve this question?

  How to find the value of x/y given the following equations?

  log base 9 (x) = log base 12 (y) = log base16 (x+y)?

  The answer is (root 5 - 1)/ 2 .

  Thanks.

• wee_ws

  13 Jun 12, 08:24

  Hi,

    It is unlikely that Cambridge will ask such a question that is not straightforward. It is important to choose questions that meet assessment objectives that are fair and reasonable. Thanks.

  Cheers,
  Wen Shih

• wee_ws

  13 Jun 12, 15:50

  Hi,

    If x/y = (sqrt(5) - 1)/2, then let y = 2 so that x = sqrt(5) - 1.

    However,

    log_9 x = log_12 y = log_16 (x + y) is not satisfied.

    The problem may be flawed, thanks.

  Cheers,
  Wen Shih

• Lohhwee

  14 Jun 12, 12:24

  Thanks  Mr Wee,

  Greatly appreciate the explainations.

  Will double-check the question from the source again.

  Cheers.

• Lohhwee

  14 Jun 12, 12:32
• wee_ws

  14 Jun 12, 13:09

  Hi,

    It is an interesting question if the mathematical details are in order :)

    Thanks in advance!

  Cheers,
  Wen Shih