Quandaries and Queries


Who is asking: Student
Level: Secondary

In general, I understand rational expressions except when it comes to solving problems such as:

x+y/2x-y - 2x/y-2x or m-4/3m-4 + 3m+2/4-3m

I am confounded by the issue of having to find a common denominator. For example, if I tried to solve these problems by multiplying both denominators they would still be uncommon. I hope these problems can be expounded on as much as possible. Thank You!




The first problem is

x + y/2x - y - 2x/y - 2x

The two denominators are 2x and y so a common denominator is 2xy. Expressing each term with denominator 2xy I get


(2x2y + y2 - 2xy2 - 4x2 - 4x2y)/2xy

(-2x2y +y2 -2xy2 - 4x2)/2xy

(P.S. I hope you did not mean something like

 (x+y)/2x(y - 2x)/(y-2x)

and forgot the parentheses.)



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