Adding and subtracting Rational Expressions

In summary, the conversation involved someone seeking help with a math problem and another person pointing out their mistake and offering a style note. The answer provided by the first person was incorrect and the second person clarified the correct answer. The conversation ended with appreciation for the help.
  • #1
caprija
34
0
I'm stuck on how to do this problem

My attempt:


Me.jpg




the answer to the second one is 3x + 2/(x+2)(x-2)

Can someone point out my mistake?
 
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  • #2
When you said that:

[tex]\frac{2}{x(x+2)} + \frac{x}{x(x-2)} = \frac{x^2-4}{(x+2))(x-2)}[/tex]

That is incorrect (take x = 1 and you get -1/3 = 1).

Also, just as a style note: you should write the fraction bar so that it extends over both the top and the bottom. (does that make sense?) For example, on your last line, you have a little bar below the 4, you should instead have a bar going from the start of the first 2x to the end of the last 2x. Unless of course you meant to write:
[tex]2x - \frac{4}{(x+2)(x-2)} + x^2 + 2x[/tex]

edit... also the "answer" you wrote is not correct.
 
Last edited:
  • #3
Alright, Thank you.
 

Related to Adding and subtracting Rational Expressions

What are rational expressions?

Rational expressions are expressions that contain fractions with variables in the numerator and/or denominator. They are also known as algebraic fractions.

How do I add or subtract rational expressions?

To add or subtract rational expressions, first find the lowest common denominator (LCD) of the fractions. Then rewrite each fraction with the LCD as the denominator. Finally, combine like terms in the numerator and simplify the resulting expression.

Can I cancel out common factors in rational expressions?

Yes, you can cancel out common factors in rational expressions. However, be careful to only cancel factors that are common to both the numerator and denominator. Canceling factors that appear only in one part of the fraction may lead to incorrect simplification.

What should I do if the denominators of the rational expressions are not the same?

If the denominators are not the same, you will need to find the LCD and rewrite each fraction with the LCD as the denominator before adding or subtracting. This is similar to finding a common denominator when adding or subtracting regular fractions.

Do I need to simplify the resulting expression after adding or subtracting rational expressions?

Yes, it is important to simplify the resulting expression after adding or subtracting rational expressions. This will ensure that the expression is in its simplest form and can help avoid errors in further calculations.

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