# LESSON 1.4 EVALUATING EXPRESSIONS

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LESSON 1.4 EVALUATING EXPRESSIONS

Homework Check & REVIEW
Class work and Homework Exercise 1.3.1 Pages 5-7 P. 14 – 16 Q # 1 - 9

LEARNING GOALS By the end of this lesson, you will be able to:
Understand the meaning of the term “operations” Understand the meaning of other words related to addition, subtraction, multiplication, division and equal. Understand what “BEDMAS” stands for. Apply BEDMAS to expressions with multiple operations.

EVALUATING EXPRESSIONS

We have to be able to “translate” words into expressions
What words indicate a particular operation? Add Subtract Minus Take away Difference Reduce(d) by Decrease(d) by Withdrawal Less than Fewer (than) Loss of Sum Plus More than Increase(d) by Perimeter Deposit Gain Greater than Up (flights of stairs) Total

We have to be able to “translate” words into expressions
What words indicate a particular operation? Multiply Divide Times Product Of Twice (×2), double (×2), triple (×3), etc. Half (×½), Third (×⅓), Quarter (×¼) Area (by) Percent (of) Square (times itself 2 times) Cube (times itself 3 times) … to the power of ___ (times itself ___ times) Split into __ parts Cost each Quotient One-half (÷2), Third (÷3), Quarter (÷4) Into Per Percent (out of 100)

FIRST – replace the variables with the known (given) value.
To EVALUATE means to FIND THE VALUE OF THE EXPRESSION when the value of the variables are known. FIRST – replace the variables with the known (given) value. THEN – follow the Order of Operations.

5 + 84 Numerical 3x + 10 Algebraic Expressions
An expression is NOT an equation because it DOES NOT have an equal sign. There are 2 types of expressions. Numerical 3x Algebraic Notice there are no equal signs in these expressions so they are not equations!

5 times 3 plus 8 (5•3) + 8 Expressions
A numerical expression contains only numbers and symbols and NO LETTERS. 5 times 3 plus 8 (5•3) + 8

An algebraic expression contains only numbers, symbols, and
Expressions An algebraic expression contains only numbers, symbols, and variables. It is sometimes referred to as a variable expression. The product of 3 and x x The sum of m and m + 8 The difference of r and r - 2

Expressions What is a variable? A variable represents an unknown value. 2) 10 – ? 1) 4 + x 4) 20 3) 5y A variable can be any letter of the alphabet since it represents an unknown.

5 • c or 5c 7 • t or 7t 6 • d or 6d Expressions
Word Phrases for multiplication are: The product of 5 and a number c Seven times a number t 6 multiplied by a number d 5 • c or 5c 7 • t or 7t 6 • d or 6d

Always write the variable AFTER the number.
Expressions The Placement rule for multiplication is: The product of 5 and a number c Seven times a number t 6 multiplied by a number d 5 • c or 5c Always write the variable AFTER the number. 7 • t or 7t 6 • d or 6d

Expressions Evaluate means to find the value of an algebraic expression by substituting numbers in for variables. m = 2 6 + m ? 6 + 2 8

Expressions Evaluate means to find the value of an algebraic expression by substituting numbers in for variables. r = 3 7 + r ? 7 + 3 10

Evaluate the variable expression when n = 6.
Expressions Evaluate the variable expression when n = 6. 1) 2) Evaluate just means solve by substitution.

Evaluate the variable expression when n = 6.
Expressions Evaluate the variable expression when n = 6. 3) 4) Evaluate just means solve by substitution.

Evaluate the algebraic expression when n = 8.
Expressions Evaluate the algebraic expression when n = 8. 1) 2)

Evaluate the expression if a = 3 and b = 4.
Expressions Evaluate the expression if a = 3 and b = 4. 1) 2)

Evaluate the expression if a = 3 and b = 4.
Expressions Evaluate the expression if a = 3 and b = 4. 3) 4)

Evaluate the expression if x = 5 and y = 3.
Expressions Evaluate the expression if x = 5 and y = 3. 2) 1)

TYPES OF EXPRESSIONS #1 An expression is NOT an equation because it does not have an equal sign. There are 2 types of expressions. NUMERICAL EXPRESSION: Contains only numbers and symbols. Example: 5 • 3 + 4 ALGEBRAIC EXPRESSION: Contains numbers, symbols, and variables. Also known as a variable expression. Example: m + 8 A VARIABLE is a letter or symbol that represents a number. Example: x