CHAPTER VARIABLES AND EXPRESSIONS

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 +Plus, sum, increased by, more than __Minus, difference, less than *Times, product,equal group of, multiply by Divided by, quotient Use diagram to help translate algebraic expressions to words

VARIABLES AND EXPRESSIONS TRANSLATE FROM ALGEBRAIC EXPRESSION TO WORDS I. Give different ways to write each algebraic expression into words Example 1: A)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

VARIABLES AND EXPRESSIONS DIAGRAM Use to help you translate words into algebraic expressions AddPut together, combine SubtractFind how much more or less MultiplyPut together equal groups divideSeparate into equal group

TRANSLATE WORDS INTO ALGEBRAIC EXPRESSIONS Example 2: A)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 additionsum, more SubtractionLess, difference, minus MultiplicationPer, times, product DivisionQuotient, ratio

TRANSLATING WORDS INTO ALGEBRAIC EXPRESSIONS

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 A)x+z x+z= 8+4 * substitute x with 8 and z with 4 = 8+4= 12 simplify

EVALUATING ALGEBRAIC EXPRESSIONS

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 Do 2-16 evens from page 9

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 subtracting