Results 1 to 2 of 2

Math Help - Can someone please proofread my homework?

  1. #1
    Newbie
    Joined
    Sep 2011
    Posts
    1

    Can someone please proofread my homework?

    I was wondering if anyone can look over my work, and tell me if i am doing everything correctly? link to the pdf file is below.

    hw1(2).pdf - File Shared from Box.net - Free Online File Storage
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Oct 2009
    Posts
    5,417
    Thanks
    718

    Re: Can someone please proofread my homework?

    Problems 1 and 2: I have not checked every cell in the truth table, but the conclusions are correct. In #2, write explicitly the answer to the question whether P ≡ Q.

    Problem 3. You need a more precise proof that x > 1 -> x^2 > x. If x > 1, then x - 1 > 0 and x > 0, so x^2 - x = x(x - 1) > 0 as the product of two positive numbers.

    Problem 4. Correct, though the formula is unusual. Usually, one has either \exists x\,(x>1\land\dots) or \forall x\,(x>1\to\dots). This is not to say that the original formula cannot occur somewhere.

    Problem 5. (y+1)^2 < y + 1 can happen when -1 < y < 0. If you choose a different value of x, you'll need a more accurate proof as well. The overall answer is correct.

    Problem 6.
    to prove this statement is false, we need to show that for any arbitrary real number y , ∃x(x^2 < y + 1) is false
    You need to find only one y. Your proof that x^2 < -2 is impossible is hard to read because it has to be written with formulas. However, in this case no further proof is necessary because \forall x\; x^2\ge 0 is a well-known fact.

    It may be a good idea to review how to solve quadratic inequalities.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. homework help
    Posted in the Discrete Math Forum
    Replies: 4
    Last Post: August 31st 2009, 04:36 AM
  2. need help with homework
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: July 20th 2009, 08:34 AM
  3. homework help
    Posted in the Algebra Forum
    Replies: 2
    Last Post: February 10th 2009, 07:12 PM
  4. Homework Help
    Posted in the Calculus Forum
    Replies: 1
    Last Post: November 2nd 2007, 01:09 PM
  5. Homework Help
    Posted in the Math Topics Forum
    Replies: 9
    Last Post: October 14th 2007, 03:00 PM

Search Tags


/mathhelpforum @mathhelpforum