Elementary Algebra Chapter 8
Roots and Radicals

From Section 8.1, 8.2, and 8.3
A number b is a square root of a if b2 = a

FACT: Every positive number has two square roots, one that is positive and one that is negative.

Definition: The principal square root of a number is its positive square root. The principale square root of 0 is 0.

FACT: The square root of a negative number is not a real number.

The Pythagorean Theorem: If the length of the hypotenuse of a right triangle is c and the lengths of its legs are a and b, then a2 + b2 = c2

Definition: A number b is a cube root of a if b3 = a

Definition:   A number b is the nth root of a if bn = a.