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Algebra 1. Ch 8.1 – Multiplication Property of Exponents. Objective. Students will use the properties of exponents to multiply exponential expressions. Before we begin. In chapter 8 we will be looking at exponents and exponential functions…
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Algebra 1 Ch 8.1 – Multiplication Property of Exponents
Objective • Students will use the properties of exponents to multiply exponential expressions
Before we begin • In chapter 8 we will be looking at exponents and exponential functions… • That is, we will be looking at how to add, subtract, multiply and divide exponents… • Once we have done that…we will apply what we have learned to simplifying expressions and solving equations… • Before we do that…let’s do a quick review of what exponents are and how they work…
Review 54 Power or Exponent Base The above number is an exponential expression. The components of an exponential expression contain a base and a power The power (exponent) tells the base how many times to multiply itself In this example the exponent (4) tells the base (5) to multiply itself 4 times and looks like this: 5 ● 5 ● 5 ● 5
Review – Common Error 54 A common error that student’s make is they multiply the base times the exponent. THAT IS INCORRECT! Let’s make a comparison: 5 ● 5 ● 5 ● 5 = 625 Correct: 5 ● 4 = 20 INCORRECT
One more thing… • When working with exponents, the exponent only applies to the number or variable directly to the left of the exponent. Example: 3x4y In this example the exponent (4) only applies to the x • If you have an expression in brackets. The exponent applies to each term within the brackets Example: (3x)2 In this example the exponent (2) applies to the 3 and the x
Properties • In this lesson we will focus on the multiplication properties of exponents… • There are a total of 3 properties that you will be expected to know how to work with. They are: • Product of Powers Property • Power of a Power Property • Power of a Product Property • This gets confusing for students because all the names sound the same… • Let’s look at each one individually…
Product of Powers Property • To multiply powers having the same base, add the exponents. Example: am● an = am+n Proof: Three factors ● a ● a ● a = a2+ 3= a5 a2 ● a3 = a ● a Two factors
Example #1 53● 56 When analyzing this expression, I notice that the base (5) is the same. That means I will use the Product of Powers Property, which states when multiplying, if the base is the same add the exponents. Solution: 53● 56 = 53+6 = 59
Example #2 x2● x3 ● x4 When analyzing this expression, I notice that the base (x) is the same. That means I will use the Product of Powers Property, which states when multiplying, if the base is the same add the exponents. Solution: x2● x3 ● x4 = x2+3+4 = x9
Power of a Power Property • To find a power of a power, multiply the exponents Example: (am)n = am●n Proof: Three factors (a2)3 = a2●3 = a ● a ● a ● a ● a ● a = a6 = a2● a2 ● a2 Six factors
Example #3 (35)2 When I analyze this expression, I see that I am multiplying exponents Therefore, I will use the Power of a Power Property to simplify the expression, which states to find the power of a power, multiply the exponents. Solution: (35)2 = 35●2 = 310
Example #4 [(a + 1)2]5 When I analyze this expression, I see that I am multiplying exponents Therefore, I will use the Power of a Power Property to simplify the expression, which states to find the power of a power, multiply the exponents. Solution: [(a + 1)2]5 = (a + 1)2●5 = (a + 1)10
Power of a Product Property • To find a power of a product, find the power of each factor and multiply Example: (a ● b)m = am ● bm This property is similar to the distributive property that you are expected to know. In this property essentially you are distributing the exponent to each term within the parenthesis
Example #5 (6 ● 5)2 When I analyze this expression, I see that I need to find the power of a product Therefore, I will use the Power of a Product Property , which states to find the power of a product, find the power of each factor and multiply Solution: (6 ● 5)2 = 62 ● 52= 36 ● 25 = 900
Example #6 (4yz)3 When I analyze this expression, I see that I need to find the power of a product Therefore, I will use the Power of a Product Property , which states to find the power of a product, find the power of each factor and multiply Solution: (4yz)3 = 43y3z3 = 64y3z3
Example # 7 (-2w)2 When I analyze this expression, I see that I need to find the power of a product Therefore, I will use the Power of a Product Property , which states to find the power of a product, find the power of each factor and multiply Solution: (-2w)2 = (-2 ● w)2 = (-2)2● w2 = 4w2 Caution: It is expected that you know -22 = (-2)●(-2) = +4
Example #8 – (2w)2 When I analyze this expression, I see that I need to find the power of a product Therefore, I will use the Power of a Product Property , which states to find the power of a product, find the power of each factor and multiply Solution: – (2w)2 = – (2 ● w)2 = – 4w2 = – (22● w2) Caution: In this example the negative sign is outside the brackets. It does not mean that the 2 inside the parenthesis is negative!
Using all 3 properties • Ok…now that we have looked at each property individually… • let’s apply what we have learned and look at simplifying an expression that contains all 3 properties • Again, the key here is to analyze the expression first…
Example #9 Simplify (4x2y)3● x5 (4x2y)3 I see that I have a power of a product in this expression Let’s simplify that first by applying the exponent 3 to each term within the parenthesis (4x2y)3● x5 = 43 ●(x2)3●y3● x5 (x2)3 I now see that I have a power of a power in this expression Let’s simplify that next by multiplying the exponents = 43 ●(x2)3●y3 ● x5 = 43 ● x6●y3 ● x5
Example #9 (Continued) = 43 ● x6●y3 ● x5 I now see that I have x6 and x5, so I will use the product of powers property which states if the base is the same add the exponents. Which looks like this: = 43 ● x11●y3 All that’s left to do is simplify the term 43 = 64● x11●y3 = 64x11y3
Comments • These concepts are relatively simple… • As you can see, to be successful here the key is to analyze the expression first…and then lay out your work in an organized step by step fashion…as I have illustrated. • As a reminder, for the remainder of this course all the problems will be multi-step… • Therefore, you will be expected to know these properties and apply them in different situations later on in the course when we work with polynomials and factoring…
Comments • On the next couple of slides are some practice problems…The answers are on the last slide… • Do the practice and then check your answers…If you do not get the same answer you must question what you did…go back and problem solve to find the error… • If you cannot find the error bring your work to me and I will help…
Your Turn • Simplify the expressions • c ● c ● c • x4 ● x5 • (43)3 • (y4)5 • (2m2)3
Your Turn • Simplify the expressions • (x3y5)4 • [(2x + 3)3]2 • (3b)3 ● b • (abc2)3(a2b)2 • –(r2st3)2(s4t)3