Range of a Function
The range of a function is the set of all output values (also known as y-values) when all elements of the domain are evaluated into the function.
Example: What is the range of the function y = {x^2} + 2?
The best way to find the range of a function is to graph it on the xy-plane.

By observing the graph of the function, the lowest value of y is 3 and it goes up to positive infinity. Therefore we can say that the range of the given function is greater than or equal to 2.
In set notation we have,
Range: \left\{ {y \in \Re |y \ge 2} \right\}
We can read this as “y is an element of the Real Numbers such that y is greater than or equal to 2“.