Question 1209311
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The portion {{{sqrt(-x)}}} has domain {{{x <= 0}}} to yield the interval notation (-infinity, 0]
The square bracket includes the endpoint 0.
This is the set of negative numbers with 0 involved as well.
I suppose you could call this the set of non-positive numbers, but I don't think that's an actual math term (I could be wrong).



If x = -2 then the denominator {{{x^2-4}}} becomes zero.
Division by zero is <u>not</u> allowed, so we must remove x = -2 from the domain.
(-infinity, 0] will update to <font color=red>(-infinity, -2) U (-2, 0]</font> which is the <font color=red>final answer</font>.
You can think of it like poking at hole at -2 on the number line.


Replace the word "infinity" with the symbol if needed. 
The positive solutions to {{{x-7=0}}} and {{{x^2-4=0}}} were never in the original domain to begin with, so we don't have to worry about them. 
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