Look for a Pattern in Integer Exponents Warm Up Evaluate. 2. 100 1000 1 3. 102 • 102 10,000 1. 103 7 10 4. 104 6 10 5. 106 1000 1 Learn to evaluate expressions with negative exponents. 10 2 10 • 10 100 ÷10 101 100 10 1 10 1 ÷10 –2 10–1 10 1 10 • 10 1 10 1 = 0.1 1 = 0.01 100 10 ÷10 ÷10 Look for a pattern in the table to extend what you know about exponents to include negative exponents. Start with what you know about positive and zero exponents. Example: Using a Pattern to Evaluate Negative Exponents Evaluate the powers of 10. A. 10–2 10–2 1 = 10 • 10 10–2 1 = 0.01 = 100 B. 10–1 10 –1 10 –1 1 = 10 = 1 10 = 0.1 Example: Using a Pattern to Evaluate Negative Exponents Continued Evaluate the powers of 10. C. 10–6 10–6 = 10–6 1 10 • 10 • 10 • 10 • 10 • 10 1 = = 0.000001 1,000,000 Try This Evaluate the powers of 10. A. 10–8 10–8 = 10–8 B. 10–9 1 = = 0.00000001 100,000,000 1 10 • 10 • 10 • 10 • 10 • 10 • 10 • 10 • 10 1 = = 0.000000001 1,000,000,000 10–9 = 10–9 1 10 • 10 • 10 • 10 • 10 • 10 • 10 • 10 Try This Evaluate the powers of 10. C. 10–7 1 10 • 10 • 10 • 10 • 10 • 10 • 10 10–7 = 10–7 1 = = 0.0000001 10,000,000 NEGATIVE EXPONENTS Words Numbers A power with a negative exponent 1 1 –3 5 = = equals 1 divided by 53 125 that power with it’s opposite exponent. Algebra b–n = 1 bn Remember! The reciprocal of a number is 1 divided by that number. Example: Evaluating Negative Exponents Evaluate. 5–3 1 53 Write the reciprocal; change the sign of the exponent. 1 5•5•5 1 125 Try This Evaluate. (–10)–3 1 –103 Write the reciprocal; change the sign of the exponent. 1 (–10)(–10)(–10) – 1 = –0.001 1000 Example: Evaluating Products and Quotients of Negative Exponents Evaluate. A. 2–5 • 23 2–5+3 Bases are the same, so add the exponents. 2 –2 1 22 1 4 Write the reciprocal; change the sign of the exponent. 3 1 2 3 Check: 2 • = 5 • 2 = 2 25 1 2•2•2 = = 2•2•2•2•2 4 –5 23 Example: Evaluating Products and Quotients of Negative Exponents Continued Evaluate. B. 65 68 65–8 6 –3 1 63 Bases are the same, so subtract the exponents. Write the reciprocal; change the sign of the exponent. 1 Check: 216 6 5= 68 1 6 •6 • 6 • 6 • 6 = 6 • 6 • 6 • 6 • 6 • 6 • 6 • 6 216 Try This Evaluate. 52 A. 53 5 2–3 5 –1 Bases are the same, so subtract the exponents. 1 51 Write the reciprocal; change the sign of the exponent. 1 5 52 = Check: 3 5 5•5 5 •5 • 5 = 1 5 Try This Evaluate. B. 7–6 • 77 Bases are the same, so add the 7–6+7 exponents. 1 7 7 7 1 –6 7 7 = 7 Check: 7 • 7 = • 7 76 76 7•7•7•7•7•7•7 7 = = 1 7•7•7•7•7•7 =7 Lesson Quiz: Part 1 Evaluate the powers of 10. 1. 10–3 0.001 2. 10–7 0.0000001 Evaluate. 3. (–6)–2 4. 74 • 7–4 5. 92 95 1 36 1 1 729 Lesson Quiz: Part 2 6. In engineering notation, a tera is equal to 1012, and a mega is equal to 106. How many megas are equal to a tera? 106