### Home > GB8I > Chapter 8 Unit 9 > Lesson INT1: 8.1.5 > Problem 8-73

If two expressions are equivalent, they can form an equation that is considered to be **always true**. For example, since .

If two expressions are equal only for certain values of the variable, they can form an equation that is considered to be **sometimes true**. For example, is equal to

*, so the equation*

*is said to be sometimes true.*

If two expressions are not equal for any value of the variable, they can form an equation that is considered to be **never true**. For example, is not equal to

*for*

*any*value of

*, so the equation*

Is the equation

The equation is sometimes true.

It is only true when .