2-2 Variables and Expressions Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day Lesson Quizzes Lesson Quizzes

2-2 Variables and Expressions Warm Up Simplify  3   15  (9 + 2)  7 

2-2 Variables and Expressions Problem of the Day How can the digits 1 through 5 be arranged in the boxes to make the greatest product? 

2-2 Variables and Expressions MA.6.A.3.1 Write and evaluate mathematical expressions…given situations. Sunshine State Standards

2-2 Variables and Expressions Vocabulary variable constant algebraic expression evaluate

2-2 Variables and Expressions A variable is a letter or symbol that represents a quantity that can change. A constant is a quantity that does not change.

2-2 Variables and Expressions An algebraic expression contains one or more variables and may contain operation symbols. So p  7 is an algebraic expression. Algebraic Expressions NOT Algebraic Expressions y85 ÷ 5 35  w + z  5 To evaluate an algebraic expression, substitute a number for the variable and then find the value by simplifying.

2-2 Variables and Expressions Evaluate the expression to find the missing values in the table. Additional Example 1A: Evaluating Algebraic Expressions Substitute for y in 5  y. y 5  y y = 16; 5  16 = y = 27; 5  = y = 35; 5  = The missing values are 135 and 175.

2-2 Variables and Expressions Evaluate the expression to find the missing values in the table. Additional Example 1B: Evaluating Algebraic Expressions z z  z = 20; 20  = 8 z = 45; __  = __ z = 60; __  = __ The missing values are 13 and 16. Substitute for z in z 

2-2 Variables and Expressions Check It Out: Example 1A Evaluate each expression to find the missing values in the table. t 8t

2-2 Variables and Expressions Evaluate each expression to find the missing values in the table. Check It Out: Example 1B m  m

2-2 Variables and Expressions Evaluate each expression to find the missing values in the table. Check It Out: Example 1C n n ÷

2-2 Variables and Expressions Evaluate each expression to find the missing values in the table. Check It Out: Example 1D b 3  (2 + b)

2-2 Variables and Expressions You can write multiplication and division expressions without using the symbols  and . Instead of... You can write... x  3 x  3 35 ÷ y x(3) 3x3x 35 y When you are multiplying a number times a variable, the number is written first. Write “3x” not “x3.” Read 3x as “three x.” Writing Math

2-2 Variables and Expressions A rectangle is 4 units wide. How many square units does the rectangle cover if it is 3, 4, 5, or 6 units long? Additional Example 2: Evaluating Expressions with Two Variables Make a table to help you find the number of square units for each length. 3 x 4 = square units lwl x w The rectangle will cover 12, 16, 20, or 24 square units. 4 x 4 = square units 5 x 4 = square units 6 x 4 = square units

2-2 Variables and Expressions Complete the table. Check It Out: Example 2A z 8  z

2-2 Variables and Expressions A rectangle is 7 units wide. What is the area of the rectangle if it is 8, 9, 10, or 11 units long? Check It Out: Example 2B 7 · 8 = 56 square units; 7 · 9 = 63 square units; 7 · 10 = 70 square units; 7 · 11 = 77 square units

2-2 Variables and Expressions 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. Check It Out: Example 2C w l = 13

2-2 Variables and Expressions Check It Out: Example 2C Continued w 2   w 5 36 units units 42 units 40 units

2-2 Variables and Expressions Standard Lesson Quiz Lesson Quizzes Lesson Quiz for Student Response Systems

2-2 Variables and Expressions 1. Evaluate the expression to find the missing values in the table. Lesson Quiz 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? lwl x w xx 2 –

2-2 Variables and Expressions 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 x5x

2-2 Variables and Expressions 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 Lesson Quiz for Student Response Systems lwl x w