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

Limits and Boundary and Func help

  1. Oct 12, 2009 #1
    How close to 4 do we have to take x so that 3x + 2 is within a distance of (a) 0.1 and (b) 0.01 from 14?

    http://i.imagehost.org/0222/Picture_1.png [Broken]

    a) Let k be any integer. Prove that if k^3 is even, then k is even.

    b) Prove that 3√2 is irrational. Hint: Mimic the proof that √2 is irrational and apply the result from part (a).

    c) Suppose two numbers a and b are irrational. Must the sum a + b be irrational? Justify your answer with an appropriate proof or counterexample

    Thanks guys!
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Oct 12, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    These look like homework problems. Are they? What have you tried on them?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook