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An Introduction to Equations

Unit 1 Lesson 8

AN INTRODUCTION TO EQUATIONS

Students will be able to:

solve equations and check solutions and

solve equations using tables and mental math.

Key Vocabulary:

Defining a variable

Four-step problem solving plan

Formula

AN INTRODUCTION TO EQUATIONS

EQUATION is a mathematical sentence that uses an equal sign (=). It can be used to represent the relationship between two quantities that have the same value.

TYPES

True equation

If the expressions on either side of the equal sign are equal.

𝟏 + πŸ— = 𝟏𝟎 𝟏𝟎 + 𝟐 = πŸ– + πŸ’

AN INTRODUCTION TO EQUATIONS

TYPES

False equation

If the expressions on either side of the equal sign are not equal.

𝟐 + πŸ– = 𝟏𝟏 𝟏𝟏 + 𝟐 = πŸ— + πŸ“

Open Sentence

If the equation contains one or more variables, and maybe a true

or a false depending on the values of its variables.

𝒙 + πŸ“ = πŸπŸ’ πŸ– + 𝒙 = πŸπŸ‘

AN INTRODUCTION TO EQUATIONS

Sample Problem 1: Tell whether each equation is true, false, or open. Explain.

A. 𝟏𝟐 + πŸπŸ– = πŸπŸ“ + πŸπŸ“

B. πŸ“ β‹… πŸ• = πŸ‘πŸ’

C. πŸ‘π’™ + 𝟏𝟐 = πŸ’πŸ–

AN INTRODUCTION TO EQUATIONS

Sample Problem 1: Tell whether each equation is true, false, or open. Explain.

A. 𝟏𝟐 + πŸπŸ– = πŸπŸ“ + πŸπŸ“ True πŸ‘πŸŽ = πŸ‘πŸŽ

B. πŸ“ β‹… πŸ• = πŸ‘πŸ’ False πŸ‘πŸ“ β‰  πŸ‘πŸ’

C. πŸ‘π’™ + 𝟏𝟐 = πŸ’πŸ– Open variable 𝒙

AN INTRODUCTION TO EQUATIONS

SOLUTION OF AN EQUATION containing a variable is a value of the variable that makes the equation true.

AN INTRODUCTION TO EQUATIONS

Sample Problem 2: Tell whether the given number is a solution of each equation.

A. Is 𝒙 = πŸ” a solution of the equation 𝒙 βˆ’ πŸπŸ’ = πŸ“?

B. Is π’š =𝟏

𝟐 a solution of the equation πŸ’π’š + 𝟐 = 𝟏𝟎?

C. Is 𝒛 = πŸ“ a solution of the equation πŸ–π’› βˆ’ πŸ” = πŸ“πŸŽ?

AN INTRODUCTION TO EQUATIONS

Sample Problem 2: Tell whether the given number is a solution of each equation.

A. Is 𝒙 = πŸ” a solution of the equation 𝒙 βˆ’ πŸπŸ’ = πŸ“? 𝒙 = πŸπŸ’ + πŸ“ 𝒙 = πŸπŸ— 𝒙 β‰  πŸ”

B. Is π’š =𝟏

𝟐 a solution of the equation πŸ’π’š + 𝟐 = 𝟏𝟎?

πŸ’π’š = 𝟏𝟎 βˆ’ 𝟐 πŸ’π’š = πŸ– π’š = 𝟐 π’š β‰ πŸ

𝟐

C. Is 𝒛 = πŸ“ a solution of the equation πŸ–π’› βˆ’ πŸ” = πŸ“πŸŽ? πŸ–π’› = πŸ“πŸŽ + πŸ” πŸ–π’› = πŸ“πŸ” 𝒛 = πŸ• 𝒛 β‰  πŸ“

AN INTRODUCTION TO EQUATIONS

Sample Problem 3: Find the solution of each equation.

A. πŸ–π’ƒ βˆ’ πŸ‘ = πŸπŸ‘

B. βˆ’πŸπŸ” = πŸπŸ” βˆ’ πŸπŸπ’™

C. βˆ’πŸ–π’› βˆ’ 𝟏𝟐 = βˆ’πŸ’

AN INTRODUCTION TO EQUATIONS

Sample Problem 3: Find the solution of each equation.

A. πŸ–π’ƒ βˆ’ πŸ‘ = πŸπŸ‘

πŸ–π’ƒ = πŸπŸ‘ + πŸ‘ πŸ–π’ƒ = πŸπŸ” 𝒃 = 𝟐

B. βˆ’πŸπŸ” = πŸπŸ” βˆ’ πŸπŸπ’™

βˆ’πŸπŸ” βˆ’ πŸπŸ” = βˆ’πŸπŸπ’™ βˆ’πŸ’πŸ = βˆ’πŸπŸπ’™ 𝟐 = 𝒙

C. βˆ’πŸ–π’› βˆ’ 𝟏𝟐 = βˆ’πŸ’

βˆ’πŸ–π’› = βˆ’πŸ’ + 𝟏𝟐 βˆ’πŸ–π’› = πŸ– 𝒛 = 𝟏

AN INTRODUCTION TO EQUATIONS

Sample Problem 4: Use a table to find the solution of each equation.

A. πŸ•π’™ + 𝟏𝟎 = πŸ’πŸ“

B. πŸ•π’™ + πŸπŸ’ = 𝟐𝟏

C. 𝟏𝟐 = πŸ’π’™ + πŸ–

AN INTRODUCTION TO EQUATIONS

Sample Problem 4: Use a table to find the solution of each equation.

A. πŸ•π’™ + 𝟏𝟎 = πŸ’πŸ“ 𝒙 = πŸ“

𝒙 πŸ•π’™ + 𝟏𝟎 = πŸ’πŸ“

πŸ‘ πŸ• πŸ‘ + 𝟏𝟎 = πŸ’πŸ“ 𝟐𝟏 + 𝟏𝟎 = πŸ’πŸ“ πŸ‘πŸ β‰  πŸ’πŸ“

πŸ’ πŸ• πŸ’ + 𝟏𝟎 = πŸ’πŸ“ πŸπŸ– + 𝟏𝟎 = πŸ’πŸ“ πŸ‘πŸ– β‰  πŸ’πŸ“

πŸ“ πŸ• πŸ“ + 𝟏𝟎 = πŸ’πŸ“ πŸ‘πŸ“ + 𝟏𝟎 = πŸ’πŸ“ πŸ’πŸ“ = πŸ’πŸ“

πŸ” πŸ• πŸ” + 𝟏𝟎 = πŸ’πŸ“ πŸ’πŸ + 𝟏𝟎 = πŸ’πŸ“ πŸ“πŸ β‰  πŸ’πŸ“

AN INTRODUCTION TO EQUATIONS

Sample Problem 4: Use a table to find the solution of each equation.

B. πŸ•π’™ + πŸπŸ’ = 𝟐𝟏 𝒙 = 𝟏

𝒙 πŸ•π’™ + πŸπŸ’ = 𝟐𝟏

𝟏 πŸ• 𝟏 + πŸπŸ’ = 𝟐𝟏 πŸ• + πŸπŸ’ = 𝟐𝟏 𝟐𝟏 = 𝟐𝟏

𝟐 πŸ• 𝟐 + πŸπŸ’ = 𝟐𝟏 πŸπŸ’ + πŸπŸ’ = 𝟐𝟏 πŸπŸ– β‰  𝟐𝟏

πŸ‘ πŸ• πŸ‘ + πŸπŸ’ = 𝟐𝟏 𝟐𝟏 + πŸπŸ’ = 𝟐𝟏 πŸ‘πŸ“ β‰  𝟐𝟏

AN INTRODUCTION TO EQUATIONS

Sample Problem 4: Use a table to find the solution of each equation.

C. 𝟏𝟐 = πŸ’π’™ + πŸ– 𝒙 = 𝟏

𝒙 𝟏𝟐 = πŸ’π’™ + πŸ–

𝟏 𝟏𝟐 = πŸ’ 𝟏 + πŸ– 𝟏𝟐 = πŸ’ + πŸ– 𝟏𝟐 = 𝟏𝟐

𝟐 𝟏𝟐 = πŸ’ 𝟐 + πŸ– 𝟏𝟐 = πŸ– + πŸ– 𝟏𝟐 β‰  πŸπŸ”

πŸ‘ 𝟏𝟐 = πŸ’ πŸ‘ + πŸ– 𝟏𝟐 = 𝟏𝟐 + πŸ– 𝟏𝟐 β‰  𝟐𝟎

AN INTRODUCTION TO EQUATIONS

Sample Problem 5: Use a table to find two consecutive integers between which the solution lies.

A. πŸ–π’™ βˆ’ 𝟐𝟎 = πŸ‘πŸ•

B. πŸ‘π’™ + πŸ’ = πŸ‘πŸ”

C. πŸ– = πŸ‘ βˆ’ πŸπ’™

AN INTRODUCTION TO EQUATIONS

Sample Problem 5: Use a table to find two consecutive integers between which the solution lies.

A. πŸ–π’™ βˆ’ 𝟐𝟎 = πŸ‘πŸ• πŸ• < 𝒙 < πŸ–

𝒙 πŸ–π’™ βˆ’ 𝟐𝟎

πŸ” πŸ– πŸ” βˆ’ 𝟐𝟎 πŸ’πŸ– βˆ’ 𝟐𝟎 πŸπŸ–

πŸ• πŸ– πŸ• βˆ’ 𝟐𝟎 πŸ“πŸ” βˆ’ 𝟐𝟎 πŸ‘πŸ”

πŸ– πŸ– πŸ– βˆ’ 𝟐𝟎 πŸ”πŸ’ βˆ’ 𝟐𝟎 πŸ’πŸ’

AN INTRODUCTION TO EQUATIONS

Sample Problem 5: Use a table to find two consecutive integers between which the solution lies.

B. πŸ‘π’™ + πŸ’ = πŸ‘πŸ” 𝟏𝟎 < 𝒙 < 𝟏𝟏

𝒙 πŸ‘π’™ + πŸ’

𝟏𝟎 πŸ‘ 𝟏𝟎 + πŸ’ πŸ‘πŸŽ + πŸ’ πŸ‘πŸ’

𝟏𝟏 πŸ‘ 𝟏𝟏 + πŸ’ πŸ‘πŸ‘ + πŸ’ πŸ‘πŸ•

𝟏𝟐 πŸ‘ 𝟏𝟐 + πŸ’ πŸ‘πŸ” + πŸ’ πŸ’πŸŽ

AN INTRODUCTION TO EQUATIONS

Sample Problem 5: Use a table to find two consecutive integers between which the solution lies.

C. πŸ– = πŸ‘ βˆ’ πŸπ’™ βˆ’πŸ < 𝒙 < βˆ’πŸ‘

𝒙 πŸ‘ βˆ’ πŸπ’™

βˆ’πŸ πŸ‘ βˆ’ 𝟐 βˆ’πŸ πŸ‘ + 𝟐 πŸ“

βˆ’πŸ πŸ‘ βˆ’ 𝟐 βˆ’πŸ πŸ‘ + πŸ’ πŸ•

βˆ’πŸ‘ πŸ‘ βˆ’ 𝟐 βˆ’πŸ‘ πŸ‘ + πŸ” πŸ—

AN INTRODUCTION TO EQUATIONS

Sample Problem 6: Find the solution of each equation using mental math or table. If the solution lies between two consecutive integers, identify those integers.

A. πŸ‘π’™ βˆ’ πŸ— = πŸπŸ’

B. πŸπŸ• = πŸ— + βˆ’π’™

C. πŸ– = 𝟐𝟏 βˆ’ πŸ•π’™

AN INTRODUCTION TO EQUATIONS

Sample Problem 6: Find the solution of each equation using mental math or table. If the solution lies between two consecutive integers, identify those integers.

A. πŸ‘π’™ βˆ’ πŸ— = πŸπŸ’ πŸ• < 𝒙 < πŸ–

𝒙 πŸ‘π’™ βˆ’ πŸ—

πŸ• πŸ‘ πŸ• βˆ’ πŸ— 𝟐𝟏 βˆ’ πŸ— 𝟏𝟐

πŸ– πŸ‘ πŸ– βˆ’ πŸ— πŸπŸ’ βˆ’ πŸ— πŸπŸ“

πŸ— πŸ‘ πŸ— βˆ’ πŸ— πŸπŸ• βˆ’ πŸ— πŸπŸ–

AN INTRODUCTION TO EQUATIONS

Sample Problem 6: Find the solution of each equation using mental math or table. If the solution lies between two consecutive integers, identify those integers.

B. πŸπŸ• = πŸ— + βˆ’π’™ 𝒙 = βˆ’πŸ–

𝒙 πŸ— + βˆ’π’™

βˆ’πŸ– πŸ— + βˆ’ βˆ’πŸ– πŸ— + πŸ– πŸπŸ•

βˆ’πŸ— πŸ— + βˆ’ βˆ’πŸ— πŸ— + πŸ— πŸπŸ–

AN INTRODUCTION TO EQUATIONS

Sample Problem 6: Find the solution of each equation using mental math or table. If the solution lies between two consecutive integers, identify those integers.

C. πŸ– = 𝟐𝟏 βˆ’ πŸ•π’™ 𝟏 < 𝒙 < 𝟐

𝒙 𝟐𝟏 βˆ’ πŸ•π’™

𝟏 𝟐𝟏 βˆ’ πŸ• 𝟏 𝟐𝟏 βˆ’ πŸ• πŸπŸ’

𝟐 𝟐𝟏 βˆ’ πŸ• 𝟐 𝟐𝟏 βˆ’ πŸπŸ’ πŸ•

πŸ‘ 𝟐𝟏 βˆ’ πŸ• πŸ‘ 𝟐𝟏 βˆ’ 𝟐𝟏 𝟎

AN INTRODUCTION TO EQUATIONS

TRANSLATING SENTENCES TO EQUATIONS:

1. Use variables to represent the unspecified numbers or measures referred to in the sentence or problem.

2. Write the verbal expressions as algebraic expressions.

Verbal Expressions that suggest the equals sign:

is equal to is is as much as

equals is the same as is identical to

AN INTRODUCTION TO EQUATIONS

Sample Problem 7: Write an equation for each sentence.

A. Fifteen times the number 𝒂 is equal to four times the sum of 𝒃 and 𝒄.

B. Three times 𝒙 subtracted from 57 equals 29.

C. The difference of 10 and a number is 5.

AN INTRODUCTION TO EQUATIONS

Sample Problem 7: Write an equation for each sentence.

A. Fifteen times the number 𝒂 is equal to four times the sum of 𝒃 and 𝒄.

πŸπŸ“ β‹… 𝒂 = πŸ’ 𝒃 + 𝒄

B. Three times 𝒙 subtracted from 57 equals 29. πŸ“πŸ• βˆ’ πŸ‘π’™ = πŸπŸ—

C. The difference of 10 and a number is 5. 𝟏𝟎 βˆ’ 𝒙 = πŸ“

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