**Problem : **
What is *x*^{2} + 3*x* - 5?

*x*^{2} + 3*x* - 5 = 5 (direct substitution).

**Problem : **
What is ?

= 0. By factoring

*x* out of the numerator and
denominator,

*f* is defined at

*x* = 0, and direct substitution works.

**Problem : **
What is 4?

4 = 4. This is a constant function.

**Problem : **
Let *f* (*x*) = *x* for *x* < 1, *f* (*x*) = 1 for *x*≥1. What is *f* (*x*)?

*f* (*x*) = 1.