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Section 7.1. Radicals and Radical Functions. Square Roots. Opposite of squaring a number is taking the square root of a number. A number b is a square root of a number a if b 2 = a. In order to find a square root of a , you need a number that, when squared, equals a.
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Section 7.1 Radicals and Radical Functions
Square Roots Opposite of squaring a number is taking the square root of a number. A number b is a square root of a number a if b2 = a. In order to find a square root of a, you need a number that, when squared, equals a.
Principal Square Roots Principal and Negative Square Roots If a is a nonnegative number, then is theprincipalor nonnegative squarerootof a and is the negative square rootof a.
REVIEW: Perfect Squares 4 = 2264 = 82x2 = x • x 9 = 3281 = 92x4 = (x2 )2 16 = 42100 = 102x6 = (x3)2 25 = 52 121 = 112 36 = 62 144 = 122 49 = 72 169 = 132
Radicands Radical expression is an expression containing a radical sign. Radicand is the expression under a radical sign. Note that if the radicand of a square root is a negative number, the radical is NOT a real number.
Radicands Example:
Perfect Squares Square roots of perfect square radicands simplify to rational numbers (numbers that can be written as a quotient of integers). Square roots of numbers that are not perfect squares (like 7, 10, etc.) are irrationalnumbers. IF REQUESTED, you can find a decimal approximation for these irrational numbers. Otherwise, leave them in radical form.
Perfect Square Roots Radicands might also contain variables and powers of variables. To avoid negative radicands, assume for this chapter that if a variable appears in the radicand, it represents positive numbers only. Example:
Cube Roots Thecube rootof a real number a is written as
List of Perfect Cubes 8= 23 -8= (-2)3 27 = 33 -27 = (-3)3 64 = 43-64 = (-4)3 125 = 53-125 = (-5)3 216 = 63-216 = (-6)3 343 = 73-343 = (-7)3 512 = 83-512 = (-8)3
Cube Roots Example:
nth Roots Other roots can be found, as well. The nth rootof a is defined as If the index, n, is even, the root is NOT a real number when a is negative. If the index is odd, the root will be a real number.
nth Roots Example: Simplify the following.