1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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: I want check my answer

  1. Feb 14, 2010 #1
    3 – If r = -1 and frist term is 1/2 find the sum of the 10 terms of a Gp

    4 - Use mathematical induction to prove that 2 + 4 + 6 ……..+ 2n = n(n+1)

    5 – Expand ( 2x – 3y)^4 by using binomial formula

    Notice :
    D. Mark i can't type my work into the text entry box. i put it in attachment i'm very sorry

    Attached Files:

    • 22.JPG
      File size:
      20.7 KB
  2. jcsd
  3. Feb 14, 2010 #2


    Staff: Mentor

    3. S10 isn't 1/11. a1 = ? r = ? n = ? Substitute these values into your formula.
    4. That's not how you do a proof by induction.
    Show that the statement is true for some base case such as n = 1. (What does the formula look like if n = 1? Is it true for that case?)
    Assume that the statement is true for n = k. (What does the formula look like for that case?)
    Use your assumption in the previous step to show that the statement is true for n = k + 1.

    5. You're sort of on the right track here, but you mixed up 2x by using 3x.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook