Question 327563
List all numbers for which the rational expression is undefined: 
x^2-4
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x^2-8x+15 
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The expression is undefined when the denominator is zero.
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Solve: x^2-8x+15 = 0
Factor:
(x-5)(x-3) = 0
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Undefined when x = 3 and when x = 5
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Cheers,
Stan H.