Perfect Squares and Square Roots (Jump to: Lecture | Video )

Here are some examples of perfect squares:

4 = 2 * 2

9 = 3 * 3

16 = 4 * 4

25 = 5 * 5

A square root is basically a square, worked backwards.

The square root of 4 is 2.

The square root of 9 is 3.

The square root of 16 is 4.

The square root of 25 is 5.

While these are simple square roots, more complicated square roots are usually found using a calculator.

Figure 1.

Here, the number 4 is under a radical, which means we are taking its square root. One thing to note is that either "2" or "-2" could be the square root of the number 4, because both 2 * 2 = 4, and (-2) * (-2) = 4. Most of the time we're only concerned with the positive square root, but in future lectures it will be important to recognize all possible roots.