Ask Me Help Desk

Ask Me Help Desk (https://www.askmehelpdesk.com/forum.php)
-   Mathematics (https://www.askmehelpdesk.com/forumdisplay.php?f=199)
-   -   Having a hard time in proving it (https://www.askmehelpdesk.com/showthread.php?t=216067)

  • May 14, 2008, 07:10 PM
    spanker1
    having a hard time in proving it
    prove that if 'n' is an integer then prove that n^2 -n+2 is even

    I tried mathematical induction to prove it
    I used s of k = k^2-k+2
    s of k+1=(K+1)^2-(k+1)+2=k^2+2k+1-k-1+2
    =k^2k+k+2
    =k(k+1)+2

    I don't know how to proceed after this.
  • May 14, 2008, 07:14 PM
    Rerepete
    If you look at k, and k+1, they are consecutive numbers, one of which has to be even. Any number multiplied by an even number is even as well.
  • May 15, 2008, 05:13 AM
    galactus
    I won't bother showing it's true for 1

    If is divisible by 2, then



    Since is divisible by 2 and 2k is divisible by 2, then

    is divisible by 2.
  • May 16, 2008, 09:13 PM
    robkelly2242
    If k is odd, k^2 must be odd, so k^2-k is even.
    If k is even, k^2 is even, and so is k^2-k.

  • All times are GMT -7. The time now is 06:42 AM.