CHAPTER 1 1-1 VARIABLES AND EXPRESSIONS

WARM -UP Add or subtract Multiply or divide -12+(-5) 5. -13*5 -12+(-5) 5. -13*5 2. 9-(-4) 6. −600÷12 3. 5+(-7) 7. 4.2*0.3 4. -8+(10) 8. 3 4 (880)

Warm –up answers Add or subtract Multiply or divide -12+(-5) -17 5. -13*5 -65 2. 9-(-4) 13 6. −600÷12 -50 3. 5+(-7) -2 7. 4.2*0.3 1.26 4. -8+(10) 2 8. 3 4 (880) 660

Variables and expressions Objectives: Translate between words and algebraic expressions Evaluate algebraic expressions

Variables and expressions vocabulary variable: is a letter or symbol used to represent a value that can change. Constant: is a value that does not change. Numerical expression: may contain only constants and/or operations. Algebraic expression: may contain variables, constants and/or operations.

Variables and expressions vocabulary examples Give examples for the following: Variables : Constants: Algebraic Expressions:

Variables and expressions Diagram Use diagram to help translate algebraic expressions to words + Plus, sum , increased by , more than __ Minus, difference, less than * Times, product ,equal group of, multiply by ÷ Divided by, quotient

Variables and Expressions Translate from algebraic expression to words I. Give different ways to write each algebraic expression into words Example 1: x+5 The sum of x and 5 Five more than x X plus 5 X increased by 5

Translate from algebraic expressions to words B) m-6 The difference of m and 6 6 less than m m minus 6 C) 3*k The product of 3 and k 3 times k

Translate from algebraic expressions to words D) g÷8 g divided y 8 The quotient of g and 8

Translate from algebraic expressions to words Student practice : Check it out 1a to 1d 1a. 4-n 1c. 9+q 1b. 𝑡 5 1d. 3(h)

Variables and expressions Diagram Use to help you translate words into algebraic expressions Add Put together, combine Subtract Find how much more or less Multiply Put together equal groups divide Separate into equal group

Translate words into algebraic expressions Example 2: Evelyn has 2 more years than her sister Adriana. Write and expression for Evelyn’s age. * a+2 B) Sam is 3 years younger than sue, who is y years old. Write an expession for sam’s age. * y-3

Translate words into algebraic expressions Words to look for that will help you with translation addition sum , more Subtraction Less, difference, minus Multiplication Per, times, product Division Quotient, ratio

Translating words into algebraic expressions C) Mario’s car is going 55 miles per hour. Write an expressions for how fast is Mario’s car going. 55 h William runs a mile in 15 minutes. Write a an expression for the number of miles that william run in m minutes. * 𝑚 15 Student Practice : check it out 2a-2c

Evaluating Algebraic Expressions Evaluate: is to find its value. Substitute: to replace To evaluate an algebraic expression substitute the variables in the expression for numbers and then simplify as needed. Hint: Usually they give the numbers you need to substitute the variables for.

Evaluating Algebraic Expressions Example 3: Evaluate each expression for x=8 , y=2 and z=4 x+z x+z= 8+4 * substitute x with 8 and z with 4 = 8+4= 12 simplify

Evaluating Algebraic Expressions B) xyz xyz = 8*2*4 substitute x,y and z with 8,2 and 4 = 8*(2*4)=8*8 simplify = 64 𝑥𝑦 𝑧 𝑥𝑦 𝑧 = 8∗2 4 substitute = 16 4 = 4 simplify

Student Practice Evaluate the following expressions give x=3,y=-7 and z=5 A) xy B) 2x+y C) x-z-y * Check it out 3a-5

Evaluating Algebraic Expressions Example 4: Challenge Example 5: Comparing cellphones plans *Lets says company AC has a plan that consists of $35 plan fee for the first 600 minutes plus 10 cents per minute pass the 600 minutes. Company BC has a plan that consists of $25 plan fee for the first 600 minutes plus 25 cents per minute pass the 600 minutes. which plan is less expensive for 800 minutes?

Variables and Expressions Homework for lesson 1-1 Page 9 and 10 17-35 evens,41

closure Today we learned about what are variables, translating algebraic expressions into words and vice versa. We also learned about evaluating algebraic expressions. Tomorrow we are going to learn chapter 1-2 solving equations by adding or substracting