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Math Help - Pre-Calc HELP

  1. #1
    trinh
    Guest

    Pre-Calc HELP ASAP! PLEASE!!

    The problem asks to solve the following expression for y in terms of x if x is not equal to zero and y is not equal to zero:

    1/X + 1/XY =y


    THanks
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  2. #2
    MHF Contributor
    Joined
    Apr 2005
    Posts
    1,631
    From 1/x +1/(xy) = y, you want to find y in terms of x only.
    Okay.

    You then have to isolate the y's, and do anything to have "y" only on one side of the equation. That will get x on the other side.

    1/x +1/(xy) = y
    Clear the fractions, multiply both sides by xy,
    y +1 = x*y^2
    Umm, we are getting a quadratic equation in "y",
    0 = x*y^2 -y -1
    Or,
    x*y^2 -y -1 = 0
    Use the Quadratic Formula,
    y = {-(-1) +,-sqrt[(-1)^2 -4(x)(-1)]} / (2*x)
    y = {1 +,-sqrt[1 +4x]} / 2x ------------------****

    That means,
    y = [1 +sqrt(1+4x)]/(2x)
    or, y = [1 -sqrt(1+4x)]/(2x)
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