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Math Help - Solve for X

  1. #1
    Dominic_089
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    Solve for X

    Ok its probably very easy, only I cant seem to figure out the order of operations to solve for X. Heres the problem
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Dominic_089 View Post
    Ok its probably very easy, only I cant seem to figure out the order of operations to solve for X. Heres the problem
    x - \frac{3}{2} + \frac{2}{5} = \frac{5}{7}

    Don't'cha just love fractions, though?

    I'd first clear those buggers out of there by multiplying both sides of the equation by 2 \cdot 5 \cdot 7 = 70:
    70 \left ( x - \frac{3}{2} + \frac{2}{5} \right ) = 70 \cdot \frac{5}{7}

    70x - 3 \cdot 35 + 2 \cdot 14 = 5 \cdot 10

    70x - 105 + 28 = 50

    Now you take it from here.

    -Dan
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  3. #3
    MHF Contributor
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    You can just type that in.

    x - (3/2) + (2/5) = (5/7)

    ...or you could learn just a hair of LaTeX

    x\;-\;\frac{3}{2}\;+\;\frac{2}{5}\;=\;\frac{5}{7}

    What order do you seek? Addition is commutative. Do it in any order you like.

    Subtract 2/5

    x\;-\;\frac{3}{2}\;=\;\frac{5}{7}\;-\;\frac{2}{5}

    Add 3/2

    x\;=\;\frac{5}{7}\;-\;\frac{2}{5}\;+\;\frac{3}{2}

    Add up the fractions and you are done.
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  4. #4
    MHF Contributor red_dog's Avatar
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    \displaystyle x-\frac{3}{2}+\frac{2}{5}=\frac{5}{7}\Rightarrow x=\frac{5}{7}+\frac{3}{2}-\frac{2}{5}

    The common denominator of the fractions from the right side is 70.
    \displaystyle x=\frac{50}{70}+\frac{105}{70}-\frac{28}{70}\Rightarrow x=\frac{127}{70}
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