How do you solve and graph #-9+2a<3a#?

1 Answer


#a > -9#


Subtract #2a# from both sides and collect like terms.

Note: When solving inequalities involving variables it is important not to divide or multiply by factors containing the variable. This is because variables can represent both positive and negative values and you would not know whether you needed to change the inequality sign round since you do not if the variable is positive or negative.

#-9 + 2a < 3a => -9 < 3a - 2a => a > -9 #

graph{x > -9 [-20, 10, -5, 5]}

The shaded area represents included values greater than -9, dotted line signifies that values on the line are not included.