Question 237901
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A rational expression is undefined for any value of the variable that will make any denominator in the expression equal to zero.  Set your denominator expression equal to zero and solve.  The roots will be the excluded values.


See http://www.algebra.com/algebra/homework/Radicals/rationalizingdenominators1.lesson

for the second part of your question.


John
*[tex \LARGE e^{i\pi} + 1 = 0]
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