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40 =15
x x - 20 This is a three part question>> first find the lcd method of solving this equations, and the second ones about cross-multiplying method to solve this equations ,The next question asked would the cross- multiplying method work for all rational equations?? Explain.

  • Algebra -

    I am guessing you are trying to type the equation

    40/x = 15/(x-20)

    The LCD is x(x-20_
    40/x (x(x-20)) = 15/(x-20) (x(x-20))
    40(x-20) = 15x
    40x - 800 = 15x
    25x = 800
    x = 32

    cross-multplying gets you directly to
    40(x-20) = 15x

    Cross-multiplying only works if your equation contains a single term on the left and a single term on the right,
    that is,
    you have to add/subract the terms first if you have more than one.
    In that case I simply multiply each term by the LCD, to get rid of my fractions.

  • Algebra -

    (1)40 =15 (2) x - 20 (2 DIFFERENT EQUATIONS)????? help please!!!!

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