Results 1 to 4 of 4

Math Help - equation

  1. #1
    Junior Member
    Joined
    Jun 2006
    Posts
    59

    equation

    Sixty cookies were to be equally distributed to x campers. When 8 campers did not want the cookies, the other campers each received 2 more cookies. Which of the following equations could be used to find the number of campers x?
    a. X^2-8X-240=0
    b. X^2-8X+240=0
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member malaygoel's Avatar
    Joined
    May 2006
    From
    India
    Posts
    648
    Quote Originally Posted by Judi
    Sixty cookies were to be equally distributed to x campers. When 8 campers did not want the cookies, the other campers each received 2 more cookies. Which of the following equations could be used to find the number of campers x?
    a. X^2-8X-240=0
    b. X^2-8X+240=0
    Your first equation is correct

    Malay
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,660
    Thanks
    600
    Hello, Judi!

    I had to baby-talk my way through this one . . .


    Sixty cookies were to be equally distributed to x campers.
    When 8 campers did not want the cookies, the other campers each received 2 more cookies.
    Which of the following equations could be used to find the number of campers x ?

    (a)\;\;x^2 - 8x - 240\:=\:0\qquad(b)\;\;x^2 - 8x + 240\:=\:0

    With x campers, each got \frac{60}{x} cookies each.

    With (x - 8) campers, each got \left(\frac{60}{x} + 2\right) cookies each.


    Since the number of cookies was 60: . (x - 8)\left(\frac{60}{x} + 2\right)\;= \;60

    Multiply: . 60 + 2x - \frac{480}{x} - 16 \;= \;60

    Simplify: . 2x - 16 - \frac{480}{x}\;=\;0

    Multiply by x:\;\;2x^2 - 16x - 480 \;= \;0


    Divide by 2:\;\;x^2 - 8x - 240 \;= \;0 . . . answer choice (a)

    ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

    I just noticed . . .

    The discriminant for equation (b) is: (-8)^2 - 4(240) . . . negative!
    . . So equation (b) has no real roots.

    So the answer is (a) . . . "by elimination"?

    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member
    Joined
    Jun 2006
    Posts
    59
    thanks...
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: April 11th 2011, 01:17 AM
  2. Partial differential equation-wave equation - dimensional analysis
    Posted in the Differential Equations Forum
    Replies: 3
    Last Post: August 28th 2009, 11:39 AM
  3. Replies: 2
    Last Post: May 18th 2009, 12:51 PM
  4. Replies: 2
    Last Post: April 28th 2009, 06:42 AM
  5. Replies: 1
    Last Post: October 23rd 2008, 03:39 AM

Search Tags


/mathhelpforum @mathhelpforum