Answer:
-6 ≤ x < ∞
Explanation:
You want the domain of the function y = √(x+6) -7.
Domain
The domain of a function is the set of x-values for which the function is defined. On a graph, it is the horizontal extent of the graph.
The square root function is undefined for negative arguments, so that limits the domain of the given function:
x+6 ≥ 0
x ≥ -6 . . . . . domain of the given function
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Additional comment
When the domain is written in interval notation, both the left and right ends of the interval must be specified.
[-6, ∞)
The square bracket identifies -6 as being part of the domain. The parenthesis is used with ∞, because that number has no specific value.