Question 50959
[The radican (5-x) must be greater than or equal to zero because you cannot find the square root of a negative number.  If the radicand is negative, it is an imaginary number.
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g(x)=(sqrt)5-x [Set 5-x>=0]
5-x>=0 [solve for x]
5>=x or x<=5 [Same value]
Than, the domain or all of the possible values for "x", must be less than or equal to 5.  Try a test case.  Pick the numbers 4 and 6.
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{{{g(4)=(sqrt(5-4))}}}
{{{g(4)=(sqrt(1))}}} = 1 [OK]
4<=5 [This is a true statement]
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{{{g(6)=(sqrt(5-6))}}} 
{{{g(6)=(sqrt(5-6))}}}
{{{g(6)=(sqrt(-1))}}} [imaginary number]
So, 6<=5 is a false statement.