Find square roots

Find square roots

As we saw 5² = 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 $\sqrt{25}$ = 5 . The negative square root of 25 is written

$\sqrt{-25}$ = -5. Since the square of any nonzero real number is positive, the

square root of a negative number, such as $\sqrt{-25}$ , is not a real number.

CAUTION

The symbol $\sqrt{}$ is used only for the positive square root, except that

$\sqrt{0}$ = 0. The symbol – $\sqrt{}$ is used for the negative square root.