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Warm Up Simplify. 1. 4 + 7 3 1 2. 87 15 5 3. 6(9 + 2) + 7 4. 35 7 5. 24. 84. 73. 25. Vocabulary. variable constant algebraic expression evaluate. A variable is a letter or symbol that represents a quantity that can change.
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Warm Up Simplify. 1. 4 + 7 3 1 2. 87 15 5 3. 6(9 + 2) + 7 4. 35 7 5 24 84 73 25
Vocabulary variable constant algebraic expression evaluate
A variable is a letter or symbol that represents a quantity that can change. A constant is a quantity that does not change.
Algebraic Expressions NOT Algebraic Expressions An algebraic expression contains one or more variables and may contain operation symbols. So p 7 is an algebraic expression. 150 + y 85 ÷ 5 35 w + z 10 + 3 5 To evaluate an algebraic expression, substitute a number for the variable and then find the value by simplifying.
y 5 y 16 80 y = 27; 5 = 27 35 y = 35; 5 = Additional Example 1A: Evaluating Algebraic Expressions Evaluate the expression to find the missing values in the table. Substitute for y in 5 y. y = 16; 5 16 = 80 27 135 135 175 35 175 The missing values are 135 and 175.
z z 5 + 4 Substitute for z in z 5 + 4. 20 20 45 60 Additional Example 1B: Evaluating Algebraic Expressions Evaluate the expression to find the missing values in the table. z = 20; 20 5 + 4 = 20 13 z = 45; __ 5 + 4 = __ 45 13 60 16 z = 60; __ 5 + 4 = __ 16 The missing values are 13 and 16.
t 8t 10 80 20 30 Check It Out: Example 1A Evaluate each expression to find the missing values in the table. 160 240
m 52 -2m 4 17 7 10 Check It Out: Example 1B Evaluate each expression to find the missing values in the table. 11 5
n n ÷ 6 - 4 60 6 48 36 Check It Out: Example 1C Evaluate each expression to find the missing values in the table. 4 2
b 3 (2 + b) 3 15 6 9 Check It Out: Example 1D Evaluate each expression to find the missing values in the table. 24 33
Instead of . . . You can write . . . y 35 Writing Math When you are multiplying a number times a variable, the number is written first. Write “3x” not “x3.” Read 3x as “three x.” You can write multiplication and division expressions without using the symbols and . x 3 x 3 x(3) 3x 35 ÷ y
Additional Example 2: Evaluating Expressions with Two Variables A rectangle is 4 units wide. How many square units does the rectangle cover if it is 3, 4, 5, or 6 units long? Make a table to help you find the number of square units for each length. 3 x 4 = square units 12 16 4 x 4 = square units 16 20 5 x 4 = square units 20 24 6 x 4 = square units 24 The rectangle will cover 12, 16, 20, or 24 square units.
z 8z + 2 7 58 9 11 Check It Out: Example 2A Complete the table. 74 90
Check It Out: Example 2B A rectangle is 7 units wide. What is the area of the rectangle if it is 8, 9, 10, or 11 units long? 7 · 8 = 56 square units; 7 · 9 = 63 square units; 7 · 10 = 70 square units; 7 · 11 = 77 square units
Check It Out: Example 2C A rectangle has a length of 13 units. The perimeter of a rectangle is twice its width plus twice its length. Complete the table to find the perimeter of the rectangle if its width is 5, 6, 7, or 8 units wide. l = 13 w
Check It Out: Example 2C Continued 38 units 40 units 42 units
Lesson Quizzes Standard Lesson Quiz Lesson Quiz for Student Response Systems
Lesson Quiz 1. Evaluate the expression to find the missing values in the table. 95 44 20 2. A rectangle is 6 units wide. What is the area of the rectangle cover if it is 2, 3, 4, or 5 units long? 12 18 24 30
Lesson Quiz for Student Response Systems 1. Evaluate the expression to find the missing values in the table. A. 67, 97, 112 B. 67, 77, 92 C. 47, 77, 92 D. 47, 77, 112
Lesson Quiz for Student Response Systems 2. A rectangle is 8 units wide. How many square units does the rectangle cover if it is 5, 6, 7, or 8 units long? A. 40, 46, 56, 66 B. 40, 48, 56, 64 C. 13, 14, 15, 16 D. 13, 15, 17, 19