**Find square roots**

As we saw 5^{2} = 5 . 5 = 25 , so 5 squared is 25. The opposite of squaring a number is

called taking its **square root. **For example, a square root of 25 is 5. Another

square root of 25 is -5 since (-5)^{2} = 25; thus, 25 has two square roots,

5 and 25.

We write the positive or *principal *square root of a number with the symbol

\sqrt{} , called a **radical sign. **For example, the positive or principal square

root of 25 is written = 5 . The negative square root of 25 is written

= -5. Since the square of any nonzero real number is positive, *the*

** square root of a negative number, such as** ,

*is not a real number***.**

**CAUTION**

The symbol is used only for the *positive *square root, except that

= 0. The symbol – is used for the negative square root.