Section 1.1 Variables and Expressions Algebra Concepts Section 1.1 Variables and Expressions

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Candy bars cost 75 cents. How many candy bars can you buy for $3.00? How many candy bars can you buy for $9.00?

3.00/.75 = 4 candy bars 9.00/.75 = 12 candy bars 3.00/.75 is a numerical expression When the price of a candy bar is unknown, a variable can be used.

Any letter can be used for a variable Let’s use p for the price of a candy bar. 3.00/p would represent how many candy bars we could buy with $3.00. 3.00/p is an algebraic expression

What’s the difference between a numerical expression and an algebraic expression?

A numerical expression has only numbers while an algebraic expression includes a variable.

Writing an algebraic expression Key words that translate into a plus sign (+): Total More than Increased by

Key words that translate into a minus (-) sign: difference fewer than less than decreased by

Keys words that translate into a multiplication ×, ∙ or ( )( ) symbol. product times

Key words that translate into a division ÷ or − symbol. quotient divided by

Write an algebraic expression for ‘Two times a number increased by 5’

2n +5 is the algebraic expression. Any letter can be used

Watch order in algebraic expressions with a subtraction symbol Order is important!!!!!!! Write an algebraic expression for: ‘10 less than a number’

The answer is n − 10 ‘A number decreased by 10’ would also be n − 10 What would the order be for ’10 fewer than a number’?