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What is the sum of all real numbers $x$ that are not in the domain of the function

$$f(x) = \frac{1}{x^2-7} + \frac{1}{x^3-8} + \frac{1}{x^4-9}~?$$

 Feb 24, 2021
 #1
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You cannot have any  ZERO denominators...

 

so    x^2   cannot = 7              x cannot   =  +- sqrt 7

         x^3 cannot equal 8        x  cannot  = 2

        x^4 cannot equal 9         x  cannot  = +- sqrt 3                sum = 2 

 Feb 24, 2021

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