### Home > A2C > Chapter 3 > Lesson 3.1.1 > Problem 3-9

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 said to be never true.*

Is the equation

Solve the equation. Rewrite

The equation is sometimes true; it is only true when