Results 1 to 2 of 2

Thread: Log questions, DID THEM ALL, Just need to make sure there correct?

  1. #1
    Jan 2009

    Log questions, DID THEM ALL, Just need to make sure there correct?

    Hey guys I'm new here. How's everyone doing? I just finished doing a bunch of log problems. If you find any faults, please tell me. This test counts for a lot, and every correct answer is worth big.

    I wrote out all the questions, and at the bottom of each I wrote my answers in bold. Please guide me guys. I need to ace this.

    1-A bacteria divides into 4 new cells every 20 minutes. If the bacteria reproduces for x hours, find the
    exponential equation that represents the increase in population as a function of time.

    I found y= 12^x

    2- Simplify:
    A- (2/3)^2X+3 = (27/8)^3X-2
    I found x=0,27

    B- 3^x+3= 13574
    I found x= 5.6617

    3- Find the inverse of the following function: f (x)= log base5(3-x)
    I found y= -5^x + 3

    4- For the following function f(x)= 3 (1/2)^4x-1 + 5, State whether the statements are true or false. Correct the false ones.

    A. It is decreasing
    B. The ordinate is 8
    C. The equation of the asymptote is y=5
    D. It is always positive
    E. It has no abcissa at the origin

    I wrote true for A, C, D and E, and I wrote the ordinate is 11 for B

    5- Find the equation of the following log function with an asymptote of x= -5.625 and passing through the point (10,3)
    I found y= log2.5 (x+5.625)

    6- Martha brought a bond for 1500.00$ at an annual rate of 4.8%, compounded semi annually. Find the rule that
    describes the value as a function of the number of years. Using the rule, find the value in 10 years.

    I found the rule was y= 1500. 1.024^2x, so in 10 years
    y= 1500 . 1.024^20= 1901,47$

    7- The following rule is used for calculating the number of years (y) it takes for a bond to reach a certain amount (x)
    y= 96.64logx - 460.34
    Calculate how much time it would take to reach 65000 and 85000.

    I put in 65000 and 85000 for x, and got 4.78 and 16.04.

    8. Find the value of the following expression:
    8(log4 32 + log2 8) - (log2 16)^2

    I found 28

    Thanks in advance guys!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    earboth's Avatar
    Jan 2006
    Quote Originally Posted by helpmeplz View Post
    2- Simplify:
    A- (2/3)^(2X+3) = (27/8)^(3X-2)
    I found x=0,27

    B- 3^(x+3)= 13574
    I found x= 5.6617

    All your considerations and calculations are OK!

    You only should use brackets to make clear which term belongs to an exponent. (See coorections in red)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: Jul 24th 2010, 02:59 PM
  2. Replies: 3
    Last Post: Jan 9th 2010, 04:23 PM
  3. Replies: 1
    Last Post: Mar 4th 2008, 07:12 PM
  4. Just cant seem to make it pass these math questions
    Posted in the Math Topics Forum
    Replies: 5
    Last Post: Nov 19th 2006, 05:15 AM
  5. Replies: 3
    Last Post: Aug 19th 2006, 11:49 PM

Search Tags

/mathhelpforum @mathhelpforum