Answer
a. always true
b. sometimes true
c. sometimes true
Work Step by Step
a. When you +1 to anything, it will never equal itself. For example, if you're adding ax + 1 it will not equal ax.
b. The definition of a variable is a symbol, usually a letter, that represents one or more numbers. In this case, the answer is sometimes true, because a variable can represent one or more numbers.
c. If in the process of solving the equation, the variable disappears and you end up with a true statement, the equation has infinitely many solutions.
