Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Intermediate Value Therom

  1. Oct 16, 2007 #1
    Hey i was jus wondering how to solve this equation i need to find a value of x when subsituted in the eqn is less than 0 so a negative value and a value of x when substituted into the eqn is greater than 0 so a positive value
    this will prove that a root exists between those domains (ie. Intermediate value theorm)

    p(x)=60x(1+x)^72-(1+x)^72+1

    Thankz for the help
     
  2. jcsd
  3. Oct 16, 2007 #2
    if you're trying to test for a # greater/less than 0, just set your equation equal to 0 and solve for x. then choose values greater/less than the value you found.
     
  4. Oct 16, 2007 #3
    hey yea thats wa i was plannin on doing but since its like ^72 i cant figure that part out
     
  5. Oct 16, 2007 #4

    EnumaElish

    User Avatar
    Science Advisor
    Homework Helper

    Just by staring at p(x) you can tell one root. Can you guess?
     
  6. Oct 16, 2007 #5
    is it 0 -1 or 1
     
  7. Oct 16, 2007 #6

    EnumaElish

    User Avatar
    Science Advisor
    Homework Helper

    Whcih do you think?
     
  8. Oct 16, 2007 #7
    hmmm ill go with -1 ?
     
  9. Oct 16, 2007 #8

    EnumaElish

    User Avatar
    Science Advisor
    Homework Helper

    Okay, plug in x = -1. What do you get?
     
  10. Oct 16, 2007 #9
    "middle-term"
     
  11. Oct 16, 2007 #10
    i got a value of 1
     
  12. Oct 16, 2007 #11
    which is greater than 0 so now i need to find a value where f(x)<0
     
  13. Oct 16, 2007 #12
    any ideas?
     
  14. Oct 16, 2007 #13

    EnumaElish

    User Avatar
    Science Advisor
    Homework Helper

    I'd try the next integers to either side.
     
  15. Oct 16, 2007 #14
    when i tried 2 , 3 and four i got really large numbers
     
  16. Oct 16, 2007 #15

    EnumaElish

    User Avatar
    Science Advisor
    Homework Helper

    You are not paying attention to the polynomial's terms.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook