Glencoe Algebra 2, Chapter 2, 2.6, Section 2.6, Problem 60

A linear inequality describes an area of the coordinate plane that has a boundary line. Every point in that region is a solution of the inequality. In simpler speak, a linear inequality is just everything on ONE side of a line on a graph.
There are a couple ways to determine whether the point (0,0) lies in the region described by the inequality, y < 2x + 3.
You could graph the inequality on a coordinate plane. However, the easiest way is by using substitution.
To do this take the x and y values from the ordered pair and substitute them into the inequality. Remember an ordered pair is always written (x,y). In this case x = 0 and y = 0.
STEPS:
0 < 2(0) + 3 0 is substituted for both the x and y values.
0 < 3 Next, simplify the expression on the right using the order of operations (multiplication first, then addition).
Since 0 < 3 is a true statement, the ordered pair (0,0) satisfies the inequality, y < 2x + 3.