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1.2 variables and expressions

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Presentation on theme: "1.2 variables and expressions"— Presentation transcript:

1 1.2 variables and expressions
Objective: Be able to tell me what is all the parts of a variable expression. Be able to substitute a number for a variable and evaluate. Students will also be able to demonstrate how to construct a variable expression

2 Definitions Algebra: math that uses symbols.
Variable: letter represents number. Ex: x and y Algebraic (variable) Expression: numbers, variables, and operations. Ex: 3x – 3y

3 Tell if examples are numerical, variable expressions or variables
3 – 4 + 3 X, Y, A 3x – 2 x 5 8y 4 – 9 3 + s

4 Evaluate Expression Key: put given #’s in for variables and solve.
Ex: Given 2 + 5y and y = 2 Given 2y – 7 and y = 5

5 Student Examples Evaluate when x = 3

6 Evaluate 2 Variable Expressions
Given x = 4 and y = 2, evaluate 3x + 2y Given 2x + 3x, evaluate when x = 5. Given 3a + 3b, solve when a = 5 and b = 7.

7 Student Examples Evaluate a = 8, b = 4 and c = 16
c – a bc b / a c – b b + c

8 Write as an algebraic expression
30 increased by a number. The quotient of 20 and a number The product of 50 and a number. Number of cars increased by 6

9 Write as algebraic expression
20 pieces of pizza divided by a group of people Two times as many. 6 feet shorter than the length of a bus. 8 dollars more for a bill.

10 Word Problem A studio charges a fee of $30 plus $5 for each portrait sheet ordered. Write an expression to find the total cost to have the pictures taken. Find the cost for 10 pictures.

11 Wrap – up Questions/Comments Ic: wkbk. Pg. 4 Hw: wkbk. Pg. 3


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