What are union and intersections mean?

Answer

When it comes to unions and intersections. It would come down to and/or statements. First, an "and" statement is where both points have to satisfy another where one goes in one direction and the other point in the other. On the other hand there are "or" statements where one or the other is correct after solving the two in equalities. From there based on the inequality signs you would either pick and open or closed circle and use the number line to point the plot in the right direction.