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Geoffrey has dimes and quarters in his pocket. The number of dimes is seven less than six times the number of quarters. Let q represent the number of quarters. Write an expression for the number of dimes.

6 q − 7

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Lauren has dimes and nickels in her purse. The number of dimes is eight more than four times the number of nickels. Let n represent the number of nickels. Write an expression for the number of dimes.

4 n + 8

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Key concepts

  • Combine like terms.
    1. Identify like terms.
    2. Rearrange the expression so like terms are together.
    3. Add the coefficients of the like terms

Practice makes perfect

Evaluate Algebraic Expressions

In the following exercises, evaluate the expression for the given value.

x 2 + 3 x 7 when x = 4

21

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x 2 + 5 x 8 when x = 6

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2 x + 4 y 5 when x = 7 , y = 8

41

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6 x + 3 y 9 when x = 6 , y = 9

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( x y ) 2 when x = 10 , y = 7

9

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( x + y ) 2 when x = 6 , y = 9

225

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a 2 + b 2 when a = 3 , b = 8

73

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r 2 s 2 when r = 12 , s = 5

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2 l + 2 w when l = 15 , w = 12

54

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2 l + 2 w when l = 18 , w = 14

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Identify Terms, Coefficients, and Like Terms

In the following exercises, list the terms in the given expression.

15 x 2 + 6 x + 2

15 x 2 , 6 x , 2

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10 y 3 + y + 2

10 y 3 , y , 2

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In the following exercises, identify the coefficient of the given term.

In the following exercises, identify all sets of like terms.

x 3 , 8 x , 14 , 8 y , 5 , 8 x 3

x 3 , 8 x 3 and 14, 5

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6 z , 3 w 2 , 1 , 6 z 2 , 4 z , w 2

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9 a , a 2 , 16 a b , 16 b 2 , 4 a b , 9 b 2

16 ab and 4 ab ; 16 b 2 and 9 b 2

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3 , 25 r 2 , 10 s , 10 r , 4 r 2 , 3 s

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Simplify Expressions by Combining Like Terms

In the following exercises, simplify the given expression by combining like terms.

7 u + 2 + 3 u + 1

10 u + 3

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7 p + 6 + 5 p + 4

12 p + 10

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10 a + 7 + 5 a 2 + 7 a 4


22 a + 1

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7 c + 4 + 6 c 3 + 9 c 1

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3 x 2 + 12 x + 11 + 14 x 2 + 8 x + 5

17 x 2 + 20 x + 16

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5 b 2 + 9 b + 10 + 2 b 2 + 3 b 4

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Translate English Phrases into Algebraic Expressions

In the following exercises, translate the given word phrase into an algebraic expression.

The sum of 8 and 12

8 + 12

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The difference of 14 and 9

14 − 9

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The product of 9 and 7

9 ⋅ 7

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The quotient of 36 and 9

36 ÷ 9

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The quotient of 42 and 7

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The difference of x and 4

x − 4

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The product of 6 and y

6 y

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The sum of 8 x and 3 x

8 x + 3 x

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The quotient of y and 3

y 3

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Eight times the difference of y and nine

8 ( y − 9)

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Seven times the difference of y and one

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Five times the sum of x and y

5 ( x + y )

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Nine times five less than twice x

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In the following exercises, write an algebraic expression.

Adele bought a skirt and a blouse. The skirt cost $15 more than the blouse. Let b represent the cost of the blouse. Write an expression for the cost of the skirt.

b + 15

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Eric has rock and classical CDs in his car. The number of rock CDs is 3 more than the number of classical CDs. Let c represent the number of classical CDs. Write an expression for the number of rock CDs.

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The number of girls in a second-grade class is 4 less than the number of boys. Let b represent the number of boys. Write an expression for the number of girls.

b − 4

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Marcella has 6 fewer male cousins than female cousins. Let f represent the number of female cousins. Write an expression for the number of boy cousins.

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Greg has nickels and pennies in his pocket. The number of pennies is seven less than twice the number of nickels. Let n represent the number of nickels. Write an expression for the number of pennies.

2 n − 7

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Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.

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Everyday math

In the following exercises, use algebraic expressions to solve the problem.

Car insurance Justin’s car insurance has a $750 deductible per incident. This means that he pays $750 and his insurance company will pay all costs beyond $750. If Justin files a claim for $2,100, how much will he pay, and how much will his insurance company pay?

He will pay $750. His insurance company will pay $1350.

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Home insurance Pam and Armando’s home insurance has a $2,500 deductible per incident. This means that they pay $2,500 and their insurance company will pay all costs beyond $2,500. If Pam and Armando file a claim for $19,400, how much will they pay, and how much will their insurance company pay?

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Writing exercises

Explain why “the sum of x and y ” is the same as “the sum of y and x ,” but “the difference of x and y ” is not the same as “the difference of y and x .” Try substituting two random numbers for x and y to help you explain.

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Explain the difference between “4 times the sum of x and y and “the sum of 4 times x and y .”

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Self check

After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.

.

After reviewing this checklist, what will you do to become confident for all objectives?

Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
what is titration
John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
what is inorganic
emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
hello friend how are you
Muhammad Reply
fine, how about you?
Mohammed
hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
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Practice Key Terms 4

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Source:  OpenStax, Prealgebra. OpenStax CNX. Jul 15, 2016 Download for free at http://legacy.cnx.org/content/col11756/1.9
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