Math 015 Section 6.6 Graphing Lines
Objective: To check solutions of an equation in two variables. Question: Is (-3, 7) a solution of y = -2x + 1 ? y = -2x + 1 Replace x with -3 Replace y with 7 7 = -2(-3) = = 7 Both sides of the equation simplify to the same thing. Yes, (-3, 7) is a solution
Question: Is (3, 2) a solution of y = x + 5 ? y = x + 5 Replace x with 3 Replace y with 2 2 = = 8 Both sides of the equation are not the same. No, (3, -2) is not a solution Objective: To check solutions of an equation in two variables.
Problem: Find the ordered pair solution of y = -3x + 1 that corresponds to x = 4 y = -3x + 1 If x = 4, then y = -3(4) + 1 so y = -11 Solution: (4, -11) Find the ordered pair solution that corresponds to x = 0 y = -3x + 1 If x = 0, then y = -3(0) + 1 so y = 1 Solution: (0, 1)
Problem: Graph the ordered-pair solutions of y = 2x – 1 when x = -2, 0, 1 and 3 y = 2x - 1 y x
Graph: y = x xy y = x
Graph y = -3x xy y = -3x + 2 2
Graph: y = 3x – 5 xy y = 3x – 5
Answer the following questions for the graph shown below. What is the y-value when x = -3 ? 2 What is the y-value when x = 5 ? -8 What is the x-value when y = -2? 1