1. 1.1 Variables in Algebra How many miles has the bike traveled? A racing biker travels down the road at 35 miles per hour. How many miles will the bike travel in 3 hours?

2. Objectives:to write and evaluate variable expressions Try the warm-up exercise Definitions: Variable - a letter that is used to represent a range of numbers. (ex. n, x, y) For Example: We can let the letter n represent the number we chose to begin the warm-up exercise. Variable expression - expressions that consist of variables, constants, and math operations. Ex. 8y, 4 + x, 16 b

3. Example 1: Describe the variable expression Variable expressionMeaningOperation a.3x, 3 x, (3)(x)__times__Multiplication b.14, 14÷y14_______yDivision y c.9 + a9________aAddition d.12 – b12_______bSubtraction Example 2: Write a variable expression a.Eight more than a number n + 8 b.Five less than a number n – 5 c.A number divided by 3 n/3 or n ÷ 3 d.Five more than three times a number 3n + 5

4. Can you now write a variable expression for our warm-up exercise? 2(n + 5) – 2n – 10 Example 3:Evaluate (solve) the variable expression When x = 5 Expressiona.) 5x b.) 40 x Substitute 5 540 5 Simplify 25 8 Example 4:Evaluate rt to find distance (d = rt) Find the distance (d) of our biker who rode 3 hours (t time in hours) and went an average speed of 35 miles per hour (r rate). Solution: d = (35)(3) d = 105 miles (What if the time changes to 30 minutes?)

5. Review vocabulary: Perimeter - the distance around a polygon (note: add together the length of the sides) Area - the space inside a closed geometric shape (note: use a formula to calculate area) A(triangle) = bhA(rectangle) = lw 2 In Class:Pg. 6 #1-4, 6-16 Homework: Pgs. 6-8 #17-27, 34-37, 50-60even Extra credit: (5 points) #40, 43, 46, 51