Results 1 to 3 of 3

Math Help - 3 ?'s that i need help on!!

  1. #1
    Newbie
    Joined
    Jun 2006
    Posts
    14

    3 ?'s that i need help on!!

    questions on attachment!!
    Attached Files Attached Files
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Global Moderator

    Joined
    Nov 2005
    From
    New York City
    Posts
    10,616
    Thanks
    9
    Question #3]
    {5 \choose 2}=\frac{5\cdot 4}{2!}=10
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,740
    Thanks
    645
    Hello, Lane!

    1. The polulation of a city in 1991 was 350,986.
    The population of the same city in 1996 was 523,026.
    Assuming that the change in the number of people is constant over five-yer periods,
    find a formula for the population of the city n five-year periods after 1991
    and predict the population of the city in 2016.

    I hope you aren't asking, "What the formula?"
    . . You can baby-talk your way through it.


    In the five years from 1991 to 1996, the population grew: 523,026 - 350,987 \,=\,172,039

    Assuming that this rate of change of the population is constant,
    . . the population will increase by 172,039 people every five years.

    Therefore, in n five-year periods after 1991, the population will be:

    . . \boxed{P \:= \:350,987 + 172,039n}


    In 2016 (25 years later, or 5 five-year periods later), the population will be:

    . . P \:=\:350,987 + 172,039(5) \:=\:\boxed{861,532}



    2. Use the binomial theorem to expand and simplify: (s - u)^5

    What part of "binomial theorem" don't you understand?


    (s - u)^5\;=\;\binom{5}{5}s^5 + \binom{5}{4}s^4(-u )+ \binom{5}{3}s^3(-u)^2 +  \binom{5}{2}s^2(-u)^3 + \binom{5}{1}s(-u)^4 + \binom{5}{0}(-u)^5

    . . . . . . =\;\boxed{s^5 - 5s^4u + 10s^3u^2 - 10s^2u^3 + 5su^4 - u^5}

    Follow Math Help Forum on Facebook and Google+


/mathhelpforum @mathhelpforum