Variables and Expressions

There are types of expressions a Numerical expression Contains only numbers and operation symbols. Ex: 8 + 5 x 2 a Variable expression contains at least one variable. Ex: 7 - a + 2 What is a Variable? A symbol usually a letter that stands for an unknown number

Evaluate each expression x + 12 for x = 8 ___________ = ________ 80 ÷ c for c = 10 ___________ = ________ 7 m for m = 5 ___________ = ________ 10 + 2p for p = 3 ___________ = ________ k ÷ 2 for k = 22 ___________ = ________ 2 ( y – 3 ) for y = 12 ___________ = ________

Writing Variable Expressions Make a list of ALL the words or phrases you can think of that describes each operation: ADDITION SUBTRACTION MULTIPLICATION DIVISION

ADDITION AND SUBTRACTION

USE your list to describe each numerical expression 5 + 8 10 - 4

MULTIPLICATION AND DIVISION

USE your list to describe each numerical expression 10 × 3 18 ÷ 6

Can those same words be used to describe variable expressions? WORD PHRASE Variable Expression The sum of m and 45 22 is more than a number w less than 55 The product of k and 10 The quotient of r and s

Write two word phrases for EACH variable expression. 2. m – n 3. 6x 4. 18 ÷ p

Writing Variable Expressions How can we write a variable expression for each word phrase? Five plus y ________________ 6 times q ________________ 2 less than x _______________