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? asked in Science & MathematicsMathematics · 8 years ago

does 84/84-x = 1 - (84)/x?

also, does: x/x+y = 1/1+y

x+y is the denominator and 1+y is the denominator as well....(just to clarify)

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  • 8 years ago
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    looks like 2 different questions, so as I understand them I will answer:

    problem 1.

    (84/84) - x = 1 - 84/x

    84/84 = 1, so we subtract 1 from both side of equation:

    -x = -84/x, here we divide both sides by -x

    x/x = 84, since x/x can only equal 1, this can not be a solution.

    problem 2.

    x/(x+y) = 1/(1+y) you left the brackets out, which is why it was necessary to further elaborate.

    First thing is to divide both sides by x

    then you have 1/(x+y) = 1/(x(1+y))

    then we can loose the numerator, by multiplying both sides by the denominators to show:

    x+y = x(1+y) then multiply out to show:

    x+y = x+xy subtract x from both sides

    y = xy divide both sides by y

    1 = x, so this does work.

  • 8 years ago

    Dear Asker,

    There is a rule that the order of actions in mathematics calculation is that division and multiplication are done before adding and subtracting. Hence: 84/84-x is actually 1-x.

    It might be that you mean there is a long division line - so it's actually 84/(84-x) - if that is the case, it should be solved as 1/(84/84-x/84) = 1/(1-x/84)

    Same goes for the next expression: the you describe it is correct, but if it's the same as the above expression, you might mean x/(x+y) which is not 1/(1+y). A solution might be 1/(1+y/x).

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