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Math Help - Finding integer value of X

  1. #1
    Senior Member vaironxxrd's Avatar
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    Finding integer value of X

    For what integer value of X is 3x+5> 11 and x-3 <1?
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by vaironxxrd View Post
    For what integer value of X is 3x+5> 11 and x-3 <1?
    3x+5>11 holds for any x>2

    x-3<1 holds for any x<4

    CB
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    Senior Member vaironxxrd's Avatar
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    Quote Originally Posted by CaptainBlack View Post
    3x+5>11 holds for any x>2

    x-3<1 holds for any x<4

    CB
    So basically is just an Equation? Theres no different math behind it ... I thought there was a formula for that
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    Quote Originally Posted by vaironxxrd View Post
    So basically is just an Equation? Theres no different math behind it ... I thought there was a formula for that
    The information given just offered upper and lower bounds for x,
    but you have to rewrite them.

    3x+5>11\Rightarrow\ 3x+5>6+5\Rightarrow\ 3x>6\Rightarrow\ 3x>3(2)\Rightarrow\ x>2

    x-3<1\Rightarrow\ x-3<4-3\Rightarrow\ x<4

    Then the allowable integer value(s) of x is much clearer.
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    Senior Member vaironxxrd's Avatar
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    Quote Originally Posted by Archie Meade View Post
    The information given just offered upper and lower bounds for x,
    but you have to rewrite them.

    3x+5>11\Rightarrow\ 3x+5>6+5\Rightarrow\ 3x>6\Rightarrow\ 3x>3(2)\Rightarrow\ x>2

    x-3<1\Rightarrow\ x-3<4-3\Rightarrow\ x<4

    Then the allowable integer value(s) of x is much clearer.
    After you do 11-5 you get the 6 but i wonder why did you put 5 again... and 3(2) Where does that 2 come froM?
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    Quote Originally Posted by vaironxxrd View Post
    After you do 11-5 you get the 6 but i wonder why did you put 5 again... and 3(2) Where does that 2 come froM?
    It's just an alternative way.
    Instead of subtracting 5 from both sides, I wrote 11=5+6 instead.
    Also, instead of dividing both sides by 3, I wrote 6=(3)2.

    It's just an alternative way to see what 3x needs to be less than etc.
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    Senior Member vaironxxrd's Avatar
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    Quote Originally Posted by Archie Meade View Post
    It's just an alternative way.
    Instead of subtracting 5 from both sides, I wrote 11=5+6 instead.
    Also, instead of dividing both sides by 3, I wrote 6=(3)2.

    It's just an alternative way to see what 3x needs to be less than etc.
    OK Got the basics down. Thanks
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  8. #8
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    Great! So what do you get as the solution to your original problem? What integer values of x satisfy both 3x+ 5> 11 and x- 3< 1?
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    Senior Member vaironxxrd's Avatar
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    Quote Originally Posted by HallsofIvy View Post
    Great! So what do you get as the solution to your original problem? What integer values of x satisfy both 3x+ 5> 11 and x- 3< 1?
    I believe 3
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