Reading & Writing Expressions

Think… How would you read these expressions? x - 45 (3 +y) (n ÷ 4) + 12 2

Objective I can read and write expressions that record operations with numbers and with letters standing for numbers.

Essential Questions What is an algebraic expression? How do you translate a word problem into an algebraic expression?

Variable Represents an unknown number Examples: 9 -x y/12 m + 14 2

Difference between: Algebraic Expression and Algebraic Equation An algebraic expression does not have an equals sign 32 + y An algebraic equation has an equals sign. 32 + y = 52

Which of the following is the correct expression? Writing Expressions Subtract 23 from x Which of the following is the correct expression? 23x 23/x x - 23 23 - x

Which of the following is the correct expression? Writing Expressions Divide y by 9 Which of the following is the correct expression? 9/y y/9 9y y-9

Which of the following is the correct expression? What about this??? Subtract 6 from x then divide by 2 Which of the following is the correct expression? 6x / 2 2 / x-6 x-6+2 x-6 / 2 Break it down

Which of the following is the correct expression? Another Example Add x to 5 then multiply by 4 Which of the following is the correct expression? (5x)4 (5 + x)4 (5 + x) / 4 4 / (5 + x)

What about this? Jake bought three pens and a notebook at the store. The notebook cost $4, but the pens didn’t have a price on them. Write an expression that would show how much the total was using (p) as your variable. 3p + $4

Another Example A plumber charges a fee of $40 plus $10 for each hour he works. Write an expression that represents the situation using the variable (h) that determines the cost. $10h + $40

Another Example The bike shop charges a flat rate of $15 for renting a bike, plus $3 an hour. Write an expression representing the cost for renting a bike using (h) as your variable. $3h + $15

Another Example The pizza shop charges $8 for a large cheese pizza plus $2 for each topping. Write an expression that represents how much it is for a large pizza using (t) as your variable. $8 + $2t

Closure Create your own word problem that involves a variable. Switch with a partner, and write the expression for their word problem.