Results 1 to 5 of 5

Math Help - Inequalities

  1. #1
    Newbie
    Joined
    Aug 2005
    Posts
    5

    Unhappy Inequalities

    I need help with understanding inequalities.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie
    Joined
    Aug 2005
    Posts
    5

    Question

    7 (x-2) < -5
    x < ________

    I dont understand the concept.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Joined
    Apr 2005
    Posts
    1,631
    I am curious. Are you a student? If yes, you are now on Inequalities in one of your Math subjects? If yes again, your teacher doesn't explain inequalities enough for you to understand them yet?
    You are using textbook that has this chapter on inequalities? You read that textbook about inequalities?

    Questions above are for your not understanding the concept of inequalities.
    You have a teacher, you have a textbook. Each of those should/could make you understand inequalities.
    Then we have internet, the Web. Search for "math, inequality".

    ---------------------
    Inequality is like equation. Or, treat inequality like it were an equation only. (I hope you know/understand equations.) Do whatever you do in an inequality as you would in an equation. What you do on one side you do it also on the other side of the equation/inequality.
    The biggest difference is that in inequalities, when you multiply or divide both sides by a negative number, you have to reverse the sense of the inequality. From > to <, or, from < to >, as the case may be.
    In equations, that cannot be done because = is = however you reverse it.

    7 (x-2) < -5 ---------(i)

    Let us say (i) is just an equation, so,
    7 (x-2) = -5
    (x-2) = -5/7
    x = -5/7 +2
    x = (-5 +2*7)/7
    x = 9/7 --------------***

    Now we do (i),
    7 (x-2) < -5
    (x-2) < -5/7
    x < -5/7 +2
    x < (-5 +2*7)/7
    x < 9/7 ----------answer

    See?

    -----------
    The reversings.

    Say, 2 -3x > 4
    So,
    -3x > 4 -2
    -3x > 2
    Divide both sides by -3, so you have to reverse the > into <,
    x < 2/(-3)
    x < -3/2

    See?

    ---------
    Edit one day after:

    2/(-3) is -2/3, not -3/2. Zeez.
    Last edited by ticbol; August 30th 2005 at 10:59 PM.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Aug 2005
    Posts
    5

    Red face Hmm...

    Im in online homeschool and literally teach myself.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Aug 2005
    Posts
    5

    Thanks

    Thankyou for the help...I kinda forgot how to do this, but know I remember.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. inequalities
    Posted in the Algebra Forum
    Replies: 7
    Last Post: August 20th 2011, 05:56 AM
  2. inequalities
    Posted in the Algebra Forum
    Replies: 0
    Last Post: March 20th 2011, 03:42 AM
  3. Inequalities
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: July 1st 2009, 05:35 AM
  4. Inequalities
    Posted in the Algebra Forum
    Replies: 4
    Last Post: June 15th 2009, 12:26 PM
  5. inequalities
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: October 14th 2008, 10:57 PM

Search Tags


/mathhelpforum @mathhelpforum