Exponents and Exponential Functions

Lesson 7

Math

Unit 6

9th Grade

Lesson 7 of 22

Objective


Write equivalent radical and rational exponent expressions. Identify quantities as rational or irrational.

Common Core Standards


Core Standards

  • N.RN.B.3 — Explain why the sum or product of two rational numbers is rational; that the sum of a rational number and an irrational number is irrational; and that the product of a nonzero rational number and an irrational number is irrational.

Foundational Standards

  • 8.EE.A.1
  • 8.EE.A.2
  • 8.NS.A.1

Criteria for Success


  1. Convert between radicals and rational exponents fluently.
  2. Apply the properties of exponents to convert between radicals and rational exponents.
  3. Determine if a given number or expression is rational or irrational. 
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Anchor Problems

25-30 minutes


Problem 1

For the problems below, determine whether each equation is True or False.

Expression True? False?

a.   $${\sqrt{32}=2^{5\over2}}$$

 

 

b.   $${16^{3\over2}=8^2}$$

 

 

c.   $${4^{1\over2}=\sqrt[4]{64}}$$

 

 

d.   $${2^8=(\sqrt[3]{16})^6}$$

 

 

e.   $${(\sqrt{64})^{1\over3}=8^{1\over6}}$$

   

Guiding Questions

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References

Smarter Balanced Assessment Consortium: Item and Task Specifications MAT.HS.SR.1.00NRN.A.152

MAT.HS.SR.1.00NRN.A.152 from Development and Design: Item and Task Specifications made available by Smarter Balanced Assessment Consortium.  © The Regents of the University of California – Smarter Balanced Assessment Consortium. Accessed May 17, 2018, 11:29 a.m..

Problem 2

In each of the following problems, a number is given. If possible, determine whether the given number is rational or irrational. In some cases, it may be impossible to determine whether the given number is rational or irrational. Justify your answers.

a.   $${4+\sqrt7}$$

b.   $${\sqrt{45}\over\sqrt{5}}$$

c.   $${6\over \pi}$$

d.   $${\sqrt2 + \sqrt3}$$

e.   $${{2+\sqrt{7}}\over{2a+\sqrt{7a^2}}}$$, where $$a$$ is a positive integer

f.   $${x+y}$$, where $$x$$ and $$y $$ are irrational numbers

Guiding Questions

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References

Illustrative Mathematics Rational or Irrational?

Rational or Irrational?, accessed on May 17, 2018, 11:34 a.m., is licensed by Illustrative Mathematics under either the CC BY 4.0 or CC BY-NC-SA 4.0. For further information, contact Illustrative Mathematics.

Problem Set

15-20 minutes


Give your students more opportunities to practice the skills in this lesson with a downloadable problem set aligned to the daily objective.

Target Task

5-10 minutes


Provide a written explanation for each question below. 

a.   Is it true that $${\left(1000^{1\over3}\right)^3=(1000^3)^{1\over3}}$$? Explain or show how you know. 

b.   Is it true that $${\left(4^{1\over2}\right)^3=(4^3)^{1\over2}}$$? Explain or show how you know. 

c.   Suppose that $$m$$ and $$n$$ are positive integers and $$b$$ is a real number so that the principal $$n^{th}$$ root of $$b$$ exists. In general, does $$\left(b^{1\over n}\right)^m=(b^m)^{1\over n}$$? Explain or show how you know. 

References

EngageNY Mathematics Algebra II > Module 3 > Topic A > Lesson 3Exit Ticket, Question #3

Algebra II > Module 3 > Topic A > Lesson 3 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..

Modified by Fishtank Learning, Inc.

Additional Practice


The following resources include problems and activities aligned to the objective of the lesson that can be used for additional practice or to create your own problem set.

Next

Simplify radical expressions.

Lesson 8
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Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Exponent Rules, Expressions, and Radicals

Topic B: Arithmetic and Geometric Sequences

Topic C: Exponential Growth and Decay

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