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Chapter P Prerequisites: Fundamental Concepts of Algebra P.3 Radicals and Rational Exponents Copyright © 2014, 2010, 2007 Pearson Education, Inc. 1 Objectives: • • • • • • • • Evaluate square roots. Simplify expressions of the form a 2 Use the product rule to simplify square roots. Use the quotient rule to simplify square roots. Add and subtract square roots. Rationalize denominators. Evaluate and perform operations with higher roots. Understand and use rational exponents. Copyright © 2014, 2010, 2007 Pearson Education, Inc. 2 Definition of the Principal Square Root. In general, if b2 = a, then b is the square root of a. Definition of the Principal Square Root: If a is a non-negative real number, the nonnegative number b such that b2 = a denoted by b a , is the principal square root of a. Copyright © 2014, 2010, 2007 Pearson Education, Inc. 3 Example: Evaluating Square Roots Evaluate: 81 9 Evaluate: 9 3 Evaluate: 36 64 100 10 Copyright © 2014, 2010, 2007 Pearson Education, Inc. 4 Simplifying Expressions of the Form Simplifying a a2 2 For any real number a, a2 a In words, the principal square root of a2 is the absolute value of a. Copyright © 2014, 2010, 2007 Pearson Education, Inc. 5 Example: Simplifying Expressions of the Form a2 Simplify: 52 5 Simplify: (5)2 25 5 Copyright © 2014, 2010, 2007 Pearson Education, Inc. 6 The Product Rule for Square Roots If a and b represent nonnegative real numbers, then ab a b and a b ab Copyright © 2014, 2010, 2007 Pearson Education, Inc. 7 Example: Using the Product Rule to Simplify Square Roots Simplify: 75 25 3 25 3 5 3 Simplify: 5 x 10 x 50x 2 25 x 2 2 25 x 2 2 Copyright © 2014, 2010, 2007 Pearson Education, Inc. 5x 2 8 The Quotient Rule for Square Roots If a and b represent nonnegative real numbers and b 0 , then a a b b and a a b b Copyright © 2014, 2010, 2007 Pearson Education, Inc. 9 Example: Using the Quotient Rule to Simplify Square Roots Simplify: 25 16 25 16 5 4 Simplify: 150 x3 150 x 3 75x 2 25 x 2 3 5 x 3 2x 2x Copyright © 2014, 2010, 2007 Pearson Education, Inc. 10 Adding and Subtracting Square Roots Two or more square roots can be combined using the distributive property provided that they have the same radicand. Such radicals are called like radicals. Copyright © 2014, 2010, 2007 Pearson Education, Inc. 11 Example: Adding and Subtracting Like Radicals Add: 8 13 9 13 (8 9) 13 17 13 Subtract: 17 x 20 17 x (1 20) 17x 19 17x Copyright © 2014, 2010, 2007 Pearson Education, Inc. 12 Rationalizing Denominators The process of rewriting a radical expression as an equivalent expression in which the denominator no longer contains any radicals is called rationalizing the denominator. If the denominator consists of the square root of a natural number that is not a perfect square, multiply the numerator and the denominator by the smallest number that produces the square root of a perfect square in the denominator. Copyright © 2014, 2010, 2007 Pearson Education, Inc. 13 Rationalizing Denominators (continued) Radical expressions that involve the sum and difference of the same two terms are called conjugates. Thus, and a b a b are conjugates. If the denominator contains two terms with one or more square roots, multiply the numerator and denominator by the conjugate of the denominator. Copyright © 2014, 2010, 2007 Pearson Education, Inc. 14 Example: Rationalizing Denominators Rationalize the denominator: 5 5 3 5 3 5 3 3 3 3 3 9 Rationalize the denominator: 8(4 5) 8 8 4 5 2 2 4 5 4 5 4 5 4 5 8(4 5) 11 32 8 5 11 Copyright © 2014, 2010, 2007 Pearson Education, Inc. 15 Definition of the Principal nth Root of a Real Number n a b means that bn = a If n, the index, is even, then a is nonnegative (a 0) and b is also nonnegative (b 0) . If n is odd, a and b can be any real numbers. The symbol n is called a radical and the expression under the radical is called the radicand. Copyright © 2014, 2010, 2007 Pearson Education, Inc. 16 Finding nth Roots of Perfect nth Powers If n is odd, n aa If n is even, n aa Copyright © 2014, 2010, 2007 Pearson Education, Inc. 17 The Product and Quotient Rules for nth Roots For all real numbers a and b, where the indicated roots represent real numbers, n n ab n a n b a na n b b and b 0 and n a n b n ab n a na n b b Copyright © 2014, 2010, 2007 Pearson Education, Inc. b 0 18 Example: Simplifying, Multiplying, and Dividing Higher Roots Simplify: 3 40 3 8 3 5 2 3 5 Simplify: 3 125 5 125 3 3 27 3 27 Copyright © 2014, 2010, 2007 Pearson Education, Inc. 19 The Definition of a m n m If n a represents a real number and n is a positive rational number, n 2 , then m n a a n m m n Also, a n am Furthermore, if a m n a is a nonzero real number, then m n 1 a m n Copyright © 2014, 2010, 2007 Pearson Education, Inc. 20 Example: Using the definition of a m n Simplify: 27 4 3 3 27 4 34 81 Copyright © 2014, 2010, 2007 Pearson Education, Inc. 21 Example: Simplifying Expressions with Rational Exponents Simplify using properties of exponents: 2 x 5 x 2 5 x x 4 3 8 3 4 3 8 3 10x 48 3 10x Copyright © 2014, 2010, 2007 Pearson Education, Inc. 12 3 10x 4 22