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Math Help - Simple Linear Algebra Question

  1. #1
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    Simple Linear Algebra Question

    Equation: 3t= \frac{5}{4}

    Step 1: t=\frac{1}{3}*\frac{5}{4}

    My question concerns this step. To isolate the variable "t" you divide by 3. It seems that should read t=\frac{5}{4} \div \frac{1}{3} however that leads to an incorrect answer. The correct way to do this apparently is t=\frac{1}{3}*\frac{5}{4}. Why do you multiply by 1/3? When you isolate "t" you divide by 3.


    Thanks for the clarification.
    Last edited by allyourbass2212; July 12th 2012 at 07:54 AM.
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  2. #2
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    Re: Simple Linear Algebra Question

    Quote Originally Posted by allyourbass2212 View Post
    My question concerns this step. To isolate the variable "t" you divide by 3. It seems that should read t=\frac{5}{4} \div \frac{1}{3}
    No, here you are trying to divide by \textstyle\frac13, not 3. Dividing by three is the same as multiplying by one-third:

    \frac54\div3 = \frac54\div\frac31 = \frac54\cdot\frac13.
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  3. #3
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    Re: Simple Linear Algebra Question

    Quote Originally Posted by Reckoner View Post
    No, here you are trying to divide by \textstyle\frac13, not 3. Dividing by three is the same as multiplying by one-third:

    \frac54\div3 = \frac54\div\frac31 = \frac54\cdot\frac13.
    Thanks, to be clear then this is for all linear algebra for instance

    Equation:  2x = 6
    Step 1: x= \frac{6}{1} \cdot \frac{1}{2}
    x= 3
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    Re: Simple Linear Algebra Question

    Quote Originally Posted by allyourbass2212 View Post
    Equation:  2x = 6
    Step 1: x= \frac{6}{1} \cdot \frac{1}{2}
    x= 3
    Correct. You could work this either way, by dividing both sides by 2 or by multiplying both sides by the reciprocal \textstyle\frac12. You get the same result regardless.
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    Re: Simple Linear Algebra Question

    attraction signs





    tutorial.math.lamar.edu/Classes/LinAlg/LinAlg.aspxHere are my online notes for my Linear Algebra course that I teach here at ... Sometimes a very good question gets asked in class
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    Re: Simple Linear Algebra Question

    Simple linear algebra is a integrated part of mathematics. sometimes students ask a difficult and logical questions in the class.

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