**In regular math books, this is called "substituting" or "evaluating"... But, those are pretty big words for something so easy.**

**Check it out:**

**We are given something like this:**

**And we need to find what this thing equals when we put a number in for x... Like**

**x = 3**

**Everywhere you see an x... stick in a 3!**

**What about x = -5?We need to be careful with the negative! Use ( )!**

**TRY IT:**

**Let x = 2:**

**Let x = -1:**