Results 1 to 4 of 4

Math Help - Need help finding a function

  1. #1
    Newbie
    Joined
    Apr 2010
    Posts
    16

    Need help finding a function

    I need to make a function using simultaneous equations that meet these requirements. It must go through the point of (3,0) and (6.25,10) and have x values of 9, -9 and -10 and the function cannot be a linear or quadratic.

    I'm having trouble because there does not seem to be enough information given to work it out because the only points we know are (3,0) and (6.25,10).

    Any help would be greatly appreciated.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,725
    Thanks
    1478
    Quote Originally Posted by mortalcyrax View Post
    I need to make a function using simultaneous equations that meet these requirements. It must go through the point of (3,0) and (6.25,10) and have x values of 9, -9 and -10 and the function cannot be a linear or quadratic.

    I'm having trouble because there does not seem to be enough information given to work it out because the only points we know are (3,0) and (6.25,10).

    Any help would be greatly appreciated.
    What does "have x values of 9, -9, and -10" mean? Simply that those x values are in the domain?

    If that and the fact that the graph contains (3, 0) and (6.25, 10), there are an infinite number of such functions. Obviously, there exist a unique linear function through those points but since you say "the function cannot be linear or quadratic", you could just try a cubic: y= ax^3+ bx^2+ cx+ d. You could pick any two of a, b, c, d arbitrarily and use the two conditions to solve for the other two.

    Or you could use a sin function: Take y= a sin(x)+ b. Then you must have a sin(3)+ b= 0 and a sin(6.25)+ b= 10. Solve those for a and b.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Apr 2010
    Posts
    16
    What does "have x values of 9, -9, and -10" mean? Simply that those x values are in the domain?
    The function must past through these points.
    I also forgot to mention that it must travel through y=9,-9 and -10 between x=3 and 6.25. It also must not reach y=10 until x=6.25...

    I have decided to take the sin approach.

    a sin(3)+ b= 0 Equation 1
    a sin(6.25)+ b= 10 Equation 2

    Subtract Equation 1 from 2 to eliminate b
    -0.057a=-10

    Divide both sides by -0.057 to solve for a
    a=176.9

    Sub a back into equation 2 to solve for b
    176.9 sin(6.25)+ b= 10
    19.26+ b= 10

    Divide both sides by 19.26 to solve for b
    b=0.52
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Apr 2010
    Posts
    16
    So is it possible to do a simultaneous equation with the information provided?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Finding a Cumulative Distribution Function and Density Function
    Posted in the Advanced Statistics Forum
    Replies: 3
    Last Post: November 17th 2011, 09:41 AM
  2. Replies: 14
    Last Post: October 7th 2011, 09:45 PM
  3. Finding probability function of moment generating function
    Posted in the Advanced Statistics Forum
    Replies: 6
    Last Post: July 4th 2011, 04:03 PM
  4. Finding function such that
    Posted in the Calculus Forum
    Replies: 1
    Last Post: February 23rd 2011, 04:11 AM
  5. finding a function
    Posted in the Calculus Forum
    Replies: 1
    Last Post: April 3rd 2010, 11:59 AM

Search Tags


/mathhelpforum @mathhelpforum