rational equation: why is it okay to multiply through?

neat

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Nov 16, 2006
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When solving a rational equation, why it is OK to remove the denominator by multiplying both sides by the LCD and why can you not do the same operation when simplifying a rational expression?
:roll:
 
3x / 2 + x / 3 is a rational expression

lcd is 6

(9x + 2x) / 6
 
When you have an equation, you have an "equals" sign and two sides, to which you can do the same thing (such as, in this case, multiplying by the LCD).

When you have only an expression, there is no "equals" and there are not two sides; there is nothing that can be equalized or otherwise fiddled with, so you have to deal with the expression as it stands.

Eliz.
 
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