1 3 Variables and Algebraic Expressions Do Now

1 -3 Variables and Algebraic Expressions Do Now Simplify. 1. 5(7) – 1 34 2. 7(18 – 11) 49 3. 22 + 17 8 + 3 161 4. 36 + 15(40 – 35) 111 5. 33 + 7(12 – 4) 83

1 -3 Variables and Algebraic Expressions 1. 1 worksheet answers 1) 69 3) 21 5) 21 7) 33 9) 28 11) 57 13) 39 15) 46 17) 18 19) 18 21) 19 23) 0 25) $10

1 -3 Variables and Algebraic Expressions Learn to evaluate algebraic expressions.

1 -3 Variables and Algebraic Expressions A variable is a letter that represents an unknown number. A constant is a number ; it cannot change. An algebraic expression consists of one or more variables. It usually contains constants and operations. Evaluate means to solve

1 -3 Variables and Algebraic Expressions Example A: Evaluate k + 9 for each value of k. k=5 k=2 k+9 5+9 14 Substitute 5 for k. Add. 2 + 9 Substitute 2 for k. 11 Add.

1 -3 Variables and Algebraic Expressions Multiplication and division of variables can be written in several ways, as shown in the table. When evaluating expressions, use the order of operations.

1 -3 Variables and Algebraic Expressions Example B: Evaluate the expression for the given value of the variable. 4 x – 3 for x = 2 4(2) – 3 8– 3 5 Substitute 2 for x. Multiply. Subtract.

1 -3 Variables and Algebraic Expressions Example C: Evaluate the expression for the given value of the variable. s ÷ 5 + s, for s = 15 15 ÷ 5 + 15 3 + 15 18 Substitute 15 for s. Divide. Add.

1 -3 Variables and Algebraic Expressions Example D: Evaluate the expression for the given value of the variable. 5 x 2 + 3 x, for x = 2 5(2)2 + 3(2) 5(4) + 3(2) 20 + 6 26 Substitute 2 for x. Evaluate the power. Multiply. Add.

1 -3 Variables and Algebraic Expressions Check your understanding Evaluate the expression for the given value of the variable. 1. ) r ÷ 3 + r, for r = 12 Substitute 12 for r. 12 ÷ 3 + 12 4 + 12 16 Divide. Add. 2. ) 4 y 2 + 2 y, for y = 3 4(3)2 + 2(3) Substitute 3 for y. 4(9) + 2(3) Evaluate the power. 36 + 6 42 Multiply. Add.

1 -3 Variables and Algebraic Expressions Check your understanding: 3. ) 6 a + 4 b, for a = 3 and b = 2. 6 a + 4 b 6 3 + 4(2) 2+8 10 Substitute 3 for a and 2 for b. Divide and multiply from left to right. Add.

1 -3 Variables and Algebraic Expressions Lesson Quiz Evaluate n + 7 for each value of n. 1. n = 25 32 2. n =31 38 Evaluate each algebraic expression for the given value of the variables 3. 6 y – 5 for y = 7 37 4. 4 x 2 + 3 x for x = 6 162 5. 56 x + 3 y for x = 4 and y = 3 23 6. The expression 7 d gives the number of days in d weeks. Evaluate 7 d for d = 12. How many days are in 12 weeks? 84

1 -3 Variables and Algebraic Expressions 7. Evaluate m + 4 for m = 19. A. 21 B. 27 C. 23 D. 28

1 -3 Variables and Algebraic Expressions 8. Evaluate 7 x – 8 for x = 5. A. 20 B. 27 C. 22 D. 32

1 -3 Variables and Algebraic Expressions 9. Evaluate 6 x 2 + 5 x for x = 5. A. 185 B. 85 C. 175 D. 50

1 -3 Variables and Algebraic Expressions 10. Evaluate 39 + 5 y for x = 3 and y = 5. x A. 38 B. 44 C. 54 D. 64

1 -3 Variables and Algebraic Expressions 11. The expression 12 n gives the number of months in n years. Evaluate 12 n for n = 3. How many months are in 3 years? A. 12 months B. 24 months C. 36 months D. 48 months