Logarithm

• bonkysleuth

  4 Mar 08, 19:30

  If log2 (y + 1) =2 log2  x+c and y=3 when x=2, find y in terms of x.

   

  There seems to be a little problem with this question. Can someone help? I'm not sure what's the 'c' for. and the '2' after each log is the subscript. thanks.

• 798

  4 Mar 08, 19:34

  c is a constant number which do not consist of x or y.

• bonkysleuth

  4 Mar 08, 19:38

  yea. but it seems to be unsolvable.

• 798

  4 Mar 08, 20:06

  is the question:

  log₂(y+1) = 2log₂(x+C) ???

• tanjun

  4 Mar 08, 21:21

  log2 (y+1) = 2log2 (x+c)

  when y = 3, x = 2

  log2 (4) = 2log2 (2+c)

  2 = 2log2 (2+c)

  log2 (2+c) = 1

  2 + c = 2

  c = 0

   

  log2 (y+1) = 2log2 (x)

• 798

  4 Mar 08, 21:24

  Originally posted by tanjun:

  log2 (y+1) = 2log2 (x+c)

  when y = 3, x = 2

  log2 (4) = 2log2 (2+c)

  2 = 2log2 (2+c)

  log2 (2+c) = 1

  2 + c = 2

  c = 0

   

  log2 (y+1) = 2log2 (x)