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

Guest Jul 17, 2017
 #2
avatar+89803 
+2

 

This one is easier than it looks

 

Any "x" that makes a denominator 0  will not be in the domain

 

So

 

x^2 - 7  = 0

x^2  = 7        take both square roots

x = ±√7   but.....notice that the sum of these = 0 

 

x^3 - 8  = 0      the only real number that makes this = 0  is 2

 

x^4 - 9  = 0

x^4  = 9       take both 4th roots

x =  ± 4√9     and, like before, the sum of these two roots  = 0

 

So.....the sum of all the numbers not in the domain  is just 2

 

 

cool cool cool

CPhill  Jul 17, 2017
 #3
avatar+7324 
+1

HMMMMM I see what you did there......   👀    cool

hectictar  Jul 17, 2017

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