2.4: Evaluate, Simplify, and Translate Expressions (Part 2) (2024)

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    Translate Words to Algebraic Expressions

    In the previous section, we listed many operation symbols that are used in algebra, and then we translated expressions and equations into word phrases and sentences. Now we’ll reverse the process and translate word phrases into algebraic expressions. The symbols and variables we’ve talked about will help us do that. They are summarized in Table \(\PageIndex{3}\).

    Table \(\PageIndex{3}\)
    Operation Phrase Expression
    Addition

    a plus b

    the sum of a and b

    a increased by b

    b more than a

    the total of a and b

    b added to a

    a + b
    Subtraction

    a minus b

    the difference of a and b

    b subtracted from a

    a decreased by b

    b less than a

    a - b
    Multiplication

    a times b

    the product of a and b

    a • b, ab, a(b), (a)(b)
    Division

    a divided by b

    the quotient of a and b

    the ratio of a and b

    b divided into a

    a ÷ b, a / b, \(\dfrac{a}{b}\), \(b \overline{) a}\)

    Look closely at these phrases using the four operations:

    • the sum of \(a\) and \(b\)
    • the difference of \(a\) and \(b\)
    • the product of \(a\) and \(b\)
    • the quotient of \(a\) and \(b\)

    Each phrase tells you to operate on two numbers. Look for the words of and and to find the numbers.

    Example \(\PageIndex{11}\): translate

    Translate each word phrase into an algebraic expression:

    1. the difference of \(20\) and \(4\)
    2. the quotient of \(10x\) and \(3\)

    Solution

    1. The key word is difference, which tells us the operation is subtraction. Look for the words of and and to find the numbers to subtract.

    the difference of \(20\) and \(4\)

    \(20\) minus \(4\)

    \(20 − 4\)

    1. The key word is quotient, which tells us the operation is division.

    the quotient of \(10x\) and \(3\)

    divide \(10x\) by \(3\)

    \(10x ÷ 3\)

    This can also be written as 1\(0x / 3\) or \(\dfrac{10x}{3}\)

    exercise \(\PageIndex{21}\)

    Translate the given word phrase into an algebraic expression:

    1. the difference of \(47\) and \(41\)
    2. the quotient of \(5x\) and \(2\)
    Answer a

    \(47-41\)

    Answer b

    \(5x\div 2\)

    exercise \(\PageIndex{22}\)

    Translate the given word phrase into an algebraic expression:

    1. the sum of \(17\) and \(19\)
    2. the product of \(7\) and \(x\)
    Answer a

    \(17+19\)

    Answer b

    \(7x\)

    How old will you be in eight years? What age is eight more years than your age now? Did you add \(8\) to your present age? Eight more than means eight added to your present age.

    How old were you seven years ago? This is seven years less than your age now. You subtract \(7\) from your present age. Seven less than means seven subtracted from your present age.

    Example \(\PageIndex{12}\): translate

    Translate each word phrase into an algebraic expression:

    1. Eight more than \(y\)
    2. Seven less than \(9z\)

    Solution

    1. The key words are more than. They tell us the operation is addition. More than means “added to”.

    Eight more than \(y\)

    Eight added to \(y\)

    \(y + 8\)

    1. The key words are less than. They tell us the operation is subtraction. Less than means “subtracted from”.

    Seven less than \(9z\)

    Seven subtracted from \(9z\)

    \(9z − 7\)

    exercise \(\PageIndex{23}\)

    Translate each word phrase into an algebraic expression:

    1. Eleven more than \(x\)
    2. Fourteen less than \(11a\)
    Answer a

    \(x+11\)

    Answer b

    \(11a-14\)

    exercise \(\PageIndex{24}\)

    Translate each word phrase into an algebraic expression:

    1. \(19\) more than \(j\)
    2. \(21\) less than \(2x\)
    Answer a

    \(j+19\)

    Answer b

    \(2x-21\)

    Example \(\PageIndex{13}\): translate

    Translate each word phrase into an algebraic expression:

    1. five times the sum of \(m\) and \(n\)
    2. the sum of five times \(m\) and \(n\)

    Solution

    1. There are two operation words: times tells us to multiply and sum tells us to add. Because we are multiplying \(5\) times the sum, we need parentheses around the sum of \(m\) and \(n\).

    five times the sum of \(m\) and \(n\)

    \(5(m + n)\)

    1. To take a sum, we look for the words of and and to see what is being added. Here we are taking the sum of five times \(m\) and \(n\).

    the sum of five times \(m\) and \(n\)

    \(5m + n\)

    Notice how the use of parentheses changes the result. In part (a), we add first and in part (b), we multiply first.

    exercise \(\PageIndex{25}\)

    Translate the word phrase into an algebraic expression:

    1. four times the sum of \(p\) and \(q\)
    2. the sum of four times \(p\) and \(q\)
    Answer a

    \(4(p+q)\)

    Answer b

    \(4p+q\)

    exercise \(\PageIndex{26}\)

    Translate the word phrase into an algebraic expression:

    1. the difference of two times \(x\) and \(8\)
    2. two times the difference of \(x\) and \(8\)
    Answer a

    \(2x-8\)

    Answer b

    \(2(x-8)\)

    Later in this course, we’ll apply our skills in algebra to solving equations. We’ll usually start by translating a word phrase to an algebraic expression. We’ll need to be clear about what the expression will represent. We’ll see how to do this in the next two examples.

    Example \(\PageIndex{14}\): write an expression

    The height of a rectangular window is 6 inches less than the width. Let w represent the width of the window. Write an expression for the height of the window.

    Solution

    Write a phrase about the height. 6 less than the width
    Substitute w for the width. 6 less than w
    Rewrite 'less than' as 'subtracted from'. 6 subtracted from w
    Translate the phrase into algebra. w - 6
    exercise \(\PageIndex{27}\)

    The length of a rectangle is \(5\) inches less than the width. Let \(w\) represent the width of the rectangle. Write an expression for the length of the rectangle.

    Answer

    \(w-5\)

    exercise \(\PageIndex{28}\)

    The width of a rectangle is \(2\) meters greater than the length. Let \(l\) represent the length of the rectangle. Write an expression for the width of the rectangle.

    Answer

    \(l+2\)

    Example \(\PageIndex{15}\): write an expression

    Blanca has dimes and quarters in her purse. The number of dimes is \(2\) less than \(5\) times the number of quarters. Let \(q\) represent the number of quarters. Write an expression for the number of dimes.

    Solution

    Write a phrase about the number of dimes. two less than five times the number of quarters
    Substitute q for the number of quarters. 2 less than five times q
    Translate 5 times q. 2 less than 5q
    Translate the phrase into algebra. 5q - 2
    exercise \(\PageIndex{29}\)

    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.

    Answer

    \(6q-7\)

    exercise \(\PageIndex{30}\)

    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.

    Answer

    \(4n+8\)

    Access Additional Online Resources

    Key Concepts

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

    Glossary

    term

    A term is a constant or the product of a constant and one or more variables.

    coefficient

    The constant that multiplies the variable(s) in a term is called the coefficient.

    like terms

    Terms that are either constants or have the same variables with the same exponents are like terms.

    evaluate

    To evaluate an algebraic expression means to find the value of the expression when the variable is replaced by a given number.

    Practice Makes Perfect

    Evaluate Algebraic Expressions

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

    1. 7x + 8 when x = 2
    2. 9x + 7 when x = 3
    3. 5x − 4 when x = 6
    4. 8x − 6 when x = 7
    5. x2 when x = 12
    6. x3 when x = 5
    7. x5 when x = 2
    8. x4 when x = 3
    9. 3x when x = 3
    10. 4x when x = 2
    11. x2 + 3x − 7 when x = 4
    12. x2 + 5x − 8 when x = 6
    13. 2x + 4y − 5 when x = 7, y = 8
    14. 6x + 3y − 9 when x = 6, y = 9
    15. (x − y)2 when x = 10, y = 7
    16. (x + y)2 when x = 6, y = 9
    17. a2 + b2 when a = 3, b = 8
    18. r2 − s2 when r = 12, s = 5
    19. 2l + 2w when l = 15, w = 12
    20. 2l + 2w when l = 18, w = 14

    Identify Terms, Coefficients, and Like Terms

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

    1. 15x2 + 6x + 2
    2. 11x2 + 8x + 5
    3. 10y3 + y + 2
    4. 9y3 + y + 5

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

    1. 8a
    2. 13m
    3. 5r2
    4. 6x3

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

    1. x3, 8x, 14, 8y, 5, 8x3
    2. 6z, 3w2, 1, 6z2, 4z, w2
    3. 9a, a2, 16ab, 16b2, 4ab, 9b2
    4. 3, 25r2, 10s, 10r, 4r2, 3s

    Simplify Expressions by Combining Like Terms

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

    1. 10x + 3x
    2. 15x + 4x
    3. 17a + 9a
    4. 18z + 9z
    5. 4c + 2c + c
    6. 6y + 4y + y
    7. 9x + 3x + 8
    8. 8a + 5a + 9
    9. 7u + 2 + 3u + 1
    10. 8d + 6 + 2d + 5
    11. 7p + 6 + 5p + 4
    12. 8x + 7 + 4x − 5
    13. 10a + 7 + 5a − 2 + 7a − 4
    14. 7c + 4 + 6c − 3 + 9c − 1
    15. 3x2 + 12x + 11 + 14x2 + 8x + 5
    16. 5b2 + 9b + 10 + 2b2 + 3b − 4

    Translate English Phrases into Algebraic Expressions

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

    1. The sum of 8 and 12
    2. The sum of 9 and 1
    3. The difference of 14 and 9
    4. 8 less than 19
    5. The product of 9 and 7
    6. The product of 8 and 7
    7. The quotient of 36 and 9
    8. The quotient of 42 and 7
    9. The difference of x and 4
    10. 3 less than x
    11. The product of 6 and y
    12. The product of 9 and y
    13. The sum of 8x and 3x
    14. The sum of 13x and 3x
    15. The quotient of y and 3
    16. The quotient of y and 8
    17. Eight times the difference of y and nine
    18. Seven times the difference of y and one
    19. Five times the sum of x and y
    20. Nine times five less than twice x

    In the following exercises, write an algebraic expression.

    1. 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.
    2. 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.
    3. 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.
    4. 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.
    5. 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.
    6. 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.

    Everyday Math

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

    1. 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?
    2. 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?

    Writing Exercises

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

    Self Check

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

    2.4: Evaluate, Simplify, and Translate Expressions (Part 2) (2)

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

    Contributors and Attributions

    2.4: Evaluate, Simplify, and Translate Expressions (Part 2) (2024)

    FAQs

    How do you evaluate and simplify expressions? ›

    To evaluate an algebraic expression means to find the value of the expression when the variable is replaced by a given number. To evaluate an expression, we substitute the given number for the variable in the expression and then simplify the expression using the order of operations.

    How to evaluate expressions in 7th grade? ›

    To evaluate an algebraic expression, you have to substitute a number for each variable and perform the arithmetic operations. In the example above, the variable x is equal to 6 since 6 + 6 = 12. If we know the value of our variables, we can replace the variables with their values and then evaluate the expression.

    What does evaluate mean in 6th grade math? ›

    To evaluate simply means finding the value of something. In mathematics, the term “evaluate” refers to finding the numerical value or result of a mathematical expression or equation. For example, to evaluate the expression “5 + 3” means to perform the addition and find the sum, which is 8.

    How do you evaluate an algebraic expression for Grade 6? ›

    To evaluate an algebraic expression, we need to know the numerical value of every variable. For each variable in the expression, we substitute the given value that it stands for, then evaluate the expression. This process of replacing the variable by their numerical value is called substitution.

    What is simplify and evaluate? ›

    Simplifying and evaluating expressions with exponents are different processes that have different purposes and outcomes. Simplifying does not change the value of the expression, but makes it easier to work with. Evaluating does change the value of the expression, but gives it a specific meaning.

    How to evaluate expressions step by step? ›

    The order of operations should always be used to evaluate the expression. For any given expression, this means solving within the parentheses, then the exponents, then multiplying or dividing from left to right, and finally adding or subtracting left to right. Not following this order will give the incorrect answer.

    How to solve simplify in mathematics? ›

    How do you simplify mathematical expressions? Order of operations play a major role in simplifying mathematical operations. The correct order of operations is: terms in parentheses, exponents, multiplication, division, addition, and, finally, subtraction. A handy acronym you can use to remember this is PEMDAS.

    What is an example of an expression in math? ›

    An expression or algebraic expression is any mathematical statement which consists of numbers, variables and an arithmetic operation between them. For example, 4m + 5 is an expression where 4m and 5 are the terms and m is the variable of the given expression separated by the arithmetic sign +.

    What does evaluate mean example? ›

    transitive verb. If you evaluate something or someone, you consider them in order to make a judgment about them, for example about how good or bad they are. The market situation is difficult to evaluate. Synonyms: assess, rate, value, judge More Synonyms of evaluate.

    What is 6th grade algebra? ›

    In sixth grade, students set the foundations for middle school algebra as they use ratios and proportions to solve problems, extend the number system to include negative numbers, and extend their work with numerical expressions to include algebraic expressions.

    How do you evaluate an expression step by step? ›

    The order of operations should always be used to evaluate the expression. For any given expression, this means solving within the parentheses, then the exponents, then multiplying or dividing from left to right, and finally adding or subtracting left to right. Not following this order will give the incorrect answer.

    How do you simplify and evaluate rational expressions? ›

    Step 1: Factor the numerator and the denominator. Step 2: List restricted values. Step 3: Cancel common factors. Step 4: Reduce to lowest terms and note any restricted values not implied by the expression.

    How do you simplify and evaluate expressions with exponents? ›

    PEMDAS has 4 rules, not 6.
    1. P = Parentheses. Do all work inside the parentheses as your 1st step.
    2. E = Exponents. All exponents come next.
    3. MD = Multiply & divide. These are in the same rule. You always work left to right within the rule. ...
    4. AS = Add & Subtract. Again, these are in the same rule.

    How do you evaluate and simplify radical expressions? ›

    Simplify a Radical Expression Using the Product Property
    • Find the largest factor in the radicand that is a perfect power of the index. Rewrite the radicand as a product of two factors, using that factor.
    • Use the product rule to rewrite the radical as the product of two radicals.
    • Simplify the root of the perfect power.
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