Section 2.1 – DAY 2 Linear Equations in Two Variables Warm Up: Describe what the graph of x = 5 would look like if graphed on the x-y plane. Given two lines, describe the relationship between the slopes if the lines are parallel. Given two lines, describe the relationship between the slopes if the lines are perpendicular. a. b. c. Vertical line through x – axis Undefined slope The slopes of two parallel lines are the same. The slopes of two perpendicular lines are opposite reciprocals.

Section 2.1 – DAY 2 Linear Equations in Two Variables After this section you should be able to: Solve real-world problems using linear equations.

Warm up: a.Use the slopes to determine the years when the earnings per share showed the greatest increase and decrease. Section 2.1 – DAY 2 Linear Equations in Two Variables Pg. 181 #35 Greatest Increase: Greatest Decrease: and 1996 – 1997 (both have a slope of.22) 1997 – 1998 (has a slope of -.35) Hint: Find two points where it looks as if it has the largest/smallest slope. Use these points to calculate the slope. The largest slope represents the greatest increase in earnings, the smallest slope represents the greatest decrease in earnings. b. Find the slope of the line segment connecting years 1988 and (1,0.98) and (11, 1.35) c. Interpret the meaning of the slope in part (b) in the context of the problem. Each year, the earnings increased.037 dollars.

Pg. 181 #34 The following are the slopes of lines representing daily revenues y in terms of time x in days. Use the slopes to interpret any change in daily revenues for a 1-day increase in time. a.The line as a slope of m = 400. Describe what the graph would look like and interpret any change in daily revenues per day. b. The line as a slope of m = 100. Describe what the graph would look like and interpret any change in daily revenues per day. c. The line as a slope of m = 0. Describe what the graph would look like and interpret any change in daily revenues per day. The revenues are increasing $400 for every 1 day. The revenues are increasing $100 for every 1 day. There is no change in revenue.

Your salary was $28,500 in 1998 and $32,900 in If your salary follows a linear growth pattern, what will your salary be in 2003? (1998, 28,500) (2000, 32,900) (2003, ???) Use your equation to predict the salary for 2003 x = y = year salary Use your equation to predict the salary for 2003

A business purchases a piece of equipment for $875. After 5 years the equipment will be outdated and have no value. Write a linear equation giving the value V of the equipment during the 5 years it will be used. (0, 875) and (5, 0) x = y = years since purchasing Value (V) This equation represents Value (V)

A contractor purchases a piece of equipment for $36,500. The equipment requires an average expenditure of $5.25 per hour for fuel and maintenance, and the operator is paid $11.50 per hour. a)Write a linear equation giving the total cost C of operating this equipment for t hours. b)Assuming that customers are charged $27 per hour of machine use, an equation which represents the profit. c) Find the ‘break-even’ point.

Section 2.1 – Day 2 Linear Equations in Two Variables After this section you should be able to: Calculate the slope of a line given two points. Write the equation of a line (in Point – Slope Form). Write the equation of a line (in Standard Form). Ax+By = C Solve real-world problems using linear equations. Homework: pg. 181 #35, 39, 97, odd Use slope to identify parallel and perpendicular lines Quiz 2.1 TUESDAY