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? asked in Science & MathematicsMathematics · 5 years ago

solve eqn. 4/(y-1) + 2/(y-3) = 6/(y-2).?

So far I know the LCD is (y-1)(y-3)(y-2). When I multiply through I get (4)(y-3)(y-2) + 2(y-1)(y-2) = 6(y-1)(y-2)

4 Answers

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  • 5 years ago

    4 / (y - 1) + 2 / (y - 3) = 6 / (y - 2)

    the first thing to notice is that y cannot be 1, 2, or 3, otherwise you will have a denominator equal to zero.

    The LCD will be the product of the three denominators. Multiply both sides by this LCD to get rid of the fractions. We now have:

    4(y - 3)(y - 2) + 2(y - 1)(y - 2) = 6(y - 1)(y - 3)

    Now simplify into a quadratic, then solve:

    4(y² - 5y + 6) + 2(y² - 3y + 2) = 6(y² - 4y + 3)

    4y² - 20y + 24 + 2y² - 6y + 4 = 6y² - 24y + 18

    6y² - 26y + 28 = 6y² - 24y + 18

    Looks like the y² terms will now cancel out, so we just have a linear equation:

    -26y + 28 = -24y + 18

    -2y = -10

    y = 5

    That is not in the list of invalid solutions, so that is your answer. As a sanity test, let's do the math:

    4 / (y - 1) + 2 / (y - 3) = 6 / (y - 2)

    4 / (5 - 1) + 2 / (5 - 3) = 6 / (5 - 2)

    4 / 4 + 2 / 2 = 6 / 3

    1 + 1 = 2

    2 = 2

    TRUE

    So it is correct. Again, the answer is:

    y = 5

  • Anonymous
    5 years ago

    Perhaps your problem is the mistake in

    (4)(y-3)(y-2) + 2(y-1)(y-2) = 6(y-1)(y-2) which should be

    (4)(y-3)(y-2) + 2(y-1)(y-2) = 6(y-1)(y-3) --The last number is 3 not 2.

  • Como
    Lv 7
    5 years ago

    4 (y - 3) (y - 2) + 2 (y - 1) (y - 2) = 6 (y - 1) (y - 3)

    4 ( y² - 5y + 6 ) + 2 (y² - 3y + 2 ) = 6 (y² - 4y + 3 )

    6y² - 26y + 28 = 6y² - 24y + 18

    10 = 2y

    y = 5

  • 5 years ago

    you have to convert to the same number in both denominators first -

    to convert you subtract -1 from both sides --1=+1 so -3--1=-3+1=2

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