Two weeks ago, I discussed the basic concepts of domain and range which I presented in an ‘algebraic way.’ In this post, I would like to discuss these concepts from a graphical perspective.
The domain of a function 
is the set of points on the x-axis where if a vertical line is drawn, it will hit a point on the graph. Take for instance, in the linear function 
, we are sure that we can always hit a point wherever we draw a vertical line. In algebraic explanation, we can always find an 
for every . Therefore, we can conclude the that domain of 
is the set of real numbers. On the other hand, if we draw a horizontal line and it hits the graph, then it is part of the range of the graph. Clearly, the range of the is also the set of real numbers.
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