The values of the variable a for which the expression
makes sense are
.
The expression
makes sense for values of a that ensure the square root operation is defined. In this case, the expression requires a non-negative value for the square root.
For the expression
to make sense:
1. a must be greater than or equal to 0 because the square root of a negative number is undefined in the real number system.
2. a can be any real number, including 0, and the expression will be meaningful.
Therefore, the values of the variable a for which the expression
makes sense are
.