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Special Types of Linear Systems. The Last Day of School!. For the last day of school the 8 th graders want to have breakfast catered. Two companies offer delicious breakfasts of bacon, eggs, hash browns, pancakes, and juice.
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The Last Day of School! • For the last day of school the 8th graders want to have breakfast catered. • Two companies offer delicious breakfasts of bacon, eggs, hash browns, pancakes, and juice. • Bravo Breakfasts charges $50 to set up the meal and $10 per person. • Crafty Catering charges $75 to set up the meal and $10 per person. • Which company is the better deal?
Write an Equation for each company and Graph it. • Bravo Breakfast: C = 50 + 10x • Crafty Catering: C = 75 + 10x • Which company is the better deal? • What do you notice about the two lines that is different from other graphs we have done? 300 200 100 C O S T 0 10 20 30 40 # of People The two lines are parallel. They will never intersect. Bravo Breakfast will always be the better deal.
Last Day of School! • On the last day of school, students want to have the option of having cinnamon rolls (x) and muffins (y) with the breakfast. • Bravo Breakfast’s equation for this combination is: 4x + 2y = 60 • Crafty Catering’s equation for this combination is: 2x + y = 30 • Which company has the better deal? • Graph these equations using x- and y-intercepts.
Graph the Equations Bravo Breakfast • 4x + 2y = 60 • 4x + 2(0) = 60 • 4x = 60 • x = 15 (15, 0) • 4(0) + 2y = 60 • 2y = 60 • y = 30 (0, 30) M U F F I N S 50 40 30 20 10 0 Crafty Catering 0 5 10 15 20 25 30 Cinnamon Rolls • 2x + y = 30 • 2x + (0) = 30 • 2x = 30 • x = 15 (15, 0) • 2(0) + y = 30 • y = 30 (0, 30) • Which company is the better deal? • What do you notice about the two lines? • The two lines are the same. Both companies offer the same deal on muffins and cinnamon rolls.
Special linear systems IntersectingParallelSame line No solution One solution Many solutions (x, y) 0 = 2 0 = 0 When you solve each system, you either get an ordered pair, a false statement, or both sides are equal.
Solve by elimination then graph to check. 3x – 2y = 3 -6x + 4y = -6 Multiply the top equations by 2 6x – 4y = 6 -6x + 4y = -6 0 = 0 (true) What does this mean?????
Graph to check: 3x – 2y = 3 -6x + 4y = -6 What do we learn about these lines [0 = 0]? They are the same line.
False Statement Parallel lines Solve by elimination then graph to check. 3x – 2y = 12 -6x + 4y = -12 Multiply top by 2 6x - 4y = 24 -6x + 4y = -12 0 = 12 (False) What does this mean?
Graph to check: 3x – 2y = 12 -6x + 4y = -12 What do we learn about these lines [0 = 12]? They are parallel lines.
Lines intersect at (2, 1) • Solve by elimination. • 2x + 3y = 7 -2x + 2y = -2 • 5y = 5 • y = 1 • Substitute and solve for x. • 2x + 3y = 7 • 2x + 3(1) = 7 • 2x = 4 • x = 2 What does this mean?
One More Time! Special linear systems: IntersectingParallelSame line No solution One solution Many solutions (x, y) 0 = 2 0 = 0 When you solve each system, you either get an ordered pair, a false statement, or both sides are equal.