Multiplying Powers With the Same Base Section 7-3

Goals Goal To multiply powers with the same base. Rubric Level 1 – Know the goals. Level 2 – Fully understand the goals. Level 3 – Use the goals to solve simple problems. Level 4 – Use the goals to solve more advanced problems. Level 5 – Adapts and applies the goals to different and more complex problems.

Vocabulary None

Multiplying Powers You have seen that exponential expressions are useful when writing very small or very large numbers. To perform operations on these numbers, you can use properties of exponents. You can also use these properties to simplify your answer. In this lesson, you will learn some properties that will help you simplify exponential expressions containing multiplication.

The following suggests a rule for multiplying powers with the same base = ( ) (2 2) = 2 6 a 3 a 2 = (a a a) (a a) = a 5 Notice that the sum of the exponents in each expression equals the exponent in the answer: = 6 and = 5. Multiplying Powers With the Same Base

Property: Multiplying Powers

A B. (n 5 )(n 7 ) n 12 n Add exponents. Simplify each expression. Write your answer in exponential form. Example: Multiplying Powers

A B. (x 2 )(x 3 ) x 5 x Add exponents. Simplify each expression. Write your answer in exponential form. Your Turn:

Simplify. A. Since the powers have the same base, keep the base and add the exponents. B. Group powers with the same base together. Add the exponents of powers with the same base. Example:

Simplify. C. D. 1 Group powers with the same base together. Add the exponents of powers with the same base. Group the positive exponents and add since they have the same base Add the like bases. Example:

A number or variable written without an exponent actually has an exponent of 1. Remember! 10 = 10 1 y = y 1

a. Simplify. Since the powers have the same base, keep the base and add the exponents. b. Group powers with the same base together. Add the exponents of powers with the same base. Your Turn:

Simplify. c. Group powers with the same base together. Add. Your Turn:

Simplify. d. Group the first two and second two terms. Divide the first group and add the second group. Multiply. Your Turn:

Multiply. A. (3a 2 )(4a 5 ) (3 ∙ 4)(a 2 ∙ a 5 ) 12a 7 Multiply coefficients. Add exponents that have the same base. B. (4x 2 y 3 )(5xy 5 ) (4 ∙ 5)(x 2 ∙ x)(y 3 ∙ y 5 ) Multiply coefficients. Add exponents that have the same base. Use the Comm. and Assoc. Properties. 3 ∙ 4 ∙ a (4 ∙ 5)(x 2 ∙ x 1 )(y 3 ∙ y 5 ) 4 ∙ 5 ∙ x ∙ y x 3 y 8 Use the Comm. and Assoc. Properties. Think: x = x 1. Example: Multiplying Powers in Algebraic Expressions

Multiply. C. (–3p 2 r)(6pr 3 s) (–3 ∙ 6)(p 2 ∙ p)(r ∙ r 3 )(s) Multiply coefficients. Add exponents that have the same base. –3 ∙ 6 ∙ p ∙ r 1+3 ∙ s –18p 3 r 4 s Use the Comm. and Assoc. Properties. (–3 ∙ 6)(p 2 ∙ p 1 )(r 1 ∙ r 3 )(s) Example: Multiplying Powers in Algebraic Expressions

Multiply. A. (2b 2 )(7b 4 ) (2 ∙ 7)(b 2 ∙ b 4 ) 14b 6 Multiply coefficients. Add exponents that have the same base. Use the Comm. and Assoc. Properties. 2 ∙ 7 ∙ b B. (4n 4 )(5n 3 )(p) (4 ∙ 5)(n 4 ∙ n 3 )(p) 20n 7 p Multiply coefficients. Add exponents that have the same base. Use the Comm. and Assoc. Properties. 4 ∙ 5 ∙ n ∙ p Your Turn:

Multiply. C. (–2a 4 b 4 )(3ab 3 c) (–2 ∙ 3)(a 4 ∙ a)(b 4 ∙ b 3 )(c) Multiply coefficients. Add exponents that have the same base. –2 ∙ 3 ∙ a ∙ b 4+3 ∙ c –6a 5 b 7 c Use the Comm. and Assoc. Properties. (–2 ∙ 3)(a 4 ∙ a 1 )(b 4 ∙ b 3 )(c) Your Turn:

Multiplying Numbers in Scientific Notation The property for multiplying powers with the same base can also be used to multiply two numbers written in scientific notation. Procedure –Combine powers of 10 using properties of exponents –Multiply the Numbers together –If necessary: Change the new Number to scientific notation Combine powers of 10 again

Multiply: (3  10 – 4 ) · (8  10 – 5 ) Express the answer in scientific notation. (3  10 – 4 ) · (8  10 – 5 ) = (3 · 8)  (10 – 4 · 10 – 5 ) = 24  10 – 9 Use the Product Rule. = (2.4  10 1 )  10 – 9 Convert 24 to scientific notation. = 2.4  10 – 8 Use the Product Rule. Example: Multiplying Using Scientific Notation

Multiply: = (7.3 · 8.1)  (10 -2 · 10 5 ) =  10 3 (7.3  10  2 )(8.1  10 5 ) 1) (7.3  10  2 )(8.1  10 5 ) =  10 4 Your Turn:

3) Multiply: (1.2  )(1.2  ) 8.5 Scientific Notation = 1.44  ) Multiply: (2.8  )(9.1  10 6 ) =  ) Multiply: (8.5  10 4 )(2  10 3 ) = 1.7  10 8

Light from the Sun travels at about miles per second. It takes about 15,000 seconds for the light to reach Neptune. Find the approximate distance from the Sun to Neptune. Write your answer in scientific notation. distance = rate  time Write 15,000 in scientific notation. Use the Commutative and Associative Properties to group. Multiply within each group. mi Example: Application

Light travels at about miles per second. Find the approximate distance that light travels in one hour. Write your answer in scientific notation. distance = rate  time Write 3,600 in scientific notation. Multiply within each group. Use the Commutative and Associative Properties to group. Your Turn:

Joke Time What do you call a pig that does karate? A pork chop! Why did the elephants get kicked out of the public pool? They kept dropping their trunks! What did the psychiatrist say when a man wearing nothing but saran wrap walked into his office? I can clearly see you’re nuts!

Assignment 7-3 Exercises Pg : #8 – 40 even, 46 – 56 even, 60, 62