Algebraic Expressions Lesson 1.3

Key Vocabulary Numerical Coefficient Constant Term Variable

Definitions A numerical coefficient is the number that multiplies the variable. The constant term is the number in the equation that will never change. The variable is the unknown number. Always represented by a letter.

Examples: 5k + 3 2n – 7 n + 8 K – 3 9n + 4

Creating an Expression Write the expression for the following: Three more than a number Seven times a number Eight less than a number A number divided by 20

When you replace a variable with a number in an algebraic expression, you evaluate the expression. It is important to remember that 7n mean 7 x n. You MUST write this as 7n, because the x can be mistaken for a variable.

Solve... A) 5k + 2 where k = 3 B) 32 – x/4 where x = 20

ALWAYS FOLLOW ORDER OF OPERATIONS! A) 5k + 2 means 5 times a number, then add 2. Replace k with 3 in the expression 5k + 2. 5k + 2 = 5 x 3 + 2 (MULTIPLY FIRST) 15 + 2 (THEN ADD) =17 ALWAYS FOLLOW ORDER OF OPERATIONS!

Order Of Operations... B rackets E xponents D ivision M ultiplication A ddition S ubtraction Follow this order for order of operations, and ALWAYS work from left to right!

B) 32 – x/4 means 32 minus a number divided by 4 B) 32 – x/4 means 32 minus a number divided by 4. Replace x with 20 in the expression 32 – x/4. Then, use Order of Operations. 32 – x/4 = 32 – 20/4 (DIVIDE FIRST) =32 – 5 (THEN SUBTRACT) = 27

Apply the Vocabulary Write down the following expressions. Identify which part of the expression is the variable, the constant term and the numerical coefficient. Then solve each expression when n = 8 A) 4n + 3 B) n – 2 C) n/2 – 3 D) 3n – 9

A little more challenging... Luis works at a local store. He earns $5 per hour during the week and $6 per hour on the weekend. A) He works 4 hours during the week and 5 hours on the weekend. Write an expression for his earnings. B) He works x hours during the week and 5 hours on the weekend. Write an expression for his earnings. C) He needs $100 to buy some new shoes. He worked 7 hours on the weekend. How many hours does he have to work during the week to have the money that he needs?

A) (4 x 5) + (5 x 6) (20) + (30) =$50 B) (5x) + (5 x 6) C) 7 x 6 = 42 100 – 42 = 58 5 x 12 = $60 When Luis works 12 hours during the week he will have enough to buy the shoes. He will have $2 left over.

Homework Textbook Page 18-19 #3,4,5,7,8,9 and reflect Workbook Lesson 1.3