Presentation on theme: "Chapter 4 Systems of Equations and Problem Solving How are systems of equations solved?"— Presentation transcript:
Chapter 4 Systems of Equations and Problem Solving How are systems of equations solved?
Activation Review Yesterday’s Warm-up
4-1 SYSTEMS OF EQUATIONS IN TWO VARIABLES How do you solve a system of equations in two variables graphically?
Vocabulary Systems of equations: two or more equations using the same variables Linear systems: each equation has two distinct variables to the first degree. Independent system: one solution Dependent system: many solutions, the same line Inconsistent system: no solution, parallel lines
Directions: Solve each equation for y Graph each equation State the point of intersection
Examples: x – y = 5 and y + 3 = 2x
Examples: 3x + y = 5 and 15x + 5y = 2
Examples: y = 2x + 3 and -4x + 2y = 6
Examples: x – 2y + 1 = 0 and x + 4y – 6 =0
What limitations do you think are affiliated with this procedure?
4-2A SOLVING SYSTEMS OF EQUATIONS —SUBSTITUTION How do you solve a system of equations in two variables by substitution?
Substitution: 1) LOOK FOR A VARIABLE W/O A COEFFICIENT 2) SOLVE FOR THAT VARIABLE 3) SUBSTITUTE THIS NEW VALUE INTO THE OTHER EQUATION exampl:e: 4x + 3y = 4 2x – y = 7
Example: 2y + x = 1 3y – 2x = 12
Examples: 5x + 3y = 6 x - y = -1
4-2A HOMEWORK PAGE(S): 166 -167 NUMBERS: 1 – 8 all USING SUBSTITUTION www.phschool.comwww.phschool.com code age-0775
Activation Review Yesterday’s warm-up
4-2B AND 4-6 SOLVING SYSTEMS OF EQUATIONS —LINEAR COMBINATION —ELIMINATION METHOD CONSISTENT AND DEPENDENT SYSTEMS How do you solve a system of equations in two variables by linear combinations? What makes a system dependent, independent, consistent, or inconsistent?
Combination/Elimination 1)LOOK FOR OR CREATE A SET OF OPPOSITES A) TO CREATE USE THE COEFFICIENT OF THE 1 ST WITH THE SECOND AND VICE VERSA B) MAKE SURE THERE WILL BE ONE + & ONE – 2) ADD THE EQUATIONS TOGETHER AND SOLVE 3) SUSTITUTE IN EITHER EQUATION AND SOLVE FOR THE REMAINING VARIABLE
Example: 4x – 2y = 7 x + 2y = 3
Example: 4x + 3y = 4 2x - y = 7
Example: 3x – 7y = 15 5x + 2y = -4
Example: 2x - y = 3 -2x + y = -3
Example: 2x - y = 3 -2x + y = 9
4-2B HOMEWORK PAGE(S): 166 -167 NUMBERS: 10 – 22 even USING LINEAR COMBINATIONS www.phschool.comwww.phschool.com code age-0775
Activation Review Yesterday’s Warm-up
4-3 USING A SYSTEM OF TWO EQUATIONS How do you translate real life problems into systems of equations?
USE ROPES: – Read the problem – Organize your thoughts in a chart – Plan the equations that will work – Evaluate the Solution – Summarize your findings
Example: The sum of the first number and a second number is -42. The first number minus the second is 52. Find the numbers 1 st numberx 2 nd numbery x + y = -42 x - y = 52
Example: Soybean meal is 16% protein and corn meal is 9% protein. How many pounds of each should be mixed together to get a 350 pound mix that is 12% protein? Soybean mealx.16 Corn mealy.09 x + y = 350.16x +.09y =.12 350
Example: A total of $1150 was invested part at 12% and part at 11%. The total yield was $133.75. How much was invested at each rate? 12% investmentx.12 11% investmenty.11 x + y = 1150.12x +.11y = 133.75
Example: One day a store sold 45 pens. One kind cost $8.75 the other $9.75. In all, $398.75 was earned. How many of each kind were sold? Type 1x8.75 Type 2y9.75 x + y = 45 8.75x + 9.75y = 398.75
4-5 USING A SYSTEM OF THREE EQUATIONS How do you translate word problems into a system of three equations?
Example: The sum of three numbers is 105. The third is 11 less than ten times the second. Twice the first is 7 more than three times the second. Find the numbers. 1 st numberx 2 nd numberY 3 rd numberz x + y + z = 105 z = 10y – 11 2x = 7 + 3y
Example: Sawmills A, B, C can produce 7400 board feet of lumber per day. A and B together can produce 4700 board feet, while B and C together can produce 5200 board feet. How many board feet can each mill produce? Mill Ax Mill By Mill Cz x + y + z = 7400 x + y = 4700 y + z = 5200
4-8 USING LINEAR PROGRAMMING EQ: What is linear programming?
VOCABULARY: Linear programming– identifies minimum or maximum of a given situation Constraints—the linear inequalities that are determined by the problem Objective—the equation that proves the minimum or maximum value.
Directions: Read the problem List the constraints List the objective Graph the inequalities finding the feasible region Solve for the vertices (the points of intersection) Test the vertices in the objective
Example: What values of y maximize P given Constraints: y≥3/2x -3 y ≤-x + 7 x≥0 y≥0 Objective: P = 3x +2y xyP
You are selling cases of mixed nuts and roasted peanuts. You can order no more than a total of 500 cans and packages and spend no more than $600. If both sell equally well, how can you maximize the profit assuming you will sell everything that you buy? xyP
Partner Problem (sample was #8) A florist has to order roses and carnations for Valentine’s Day. The florist needs to decide how many dozen roses and carnations should be ordered to obtain a maximum profit. Roses: The florist’s cost is $20 per dozen, the profit over cost is $20 per dozen. Carnations: The florist’s cost is $5 per dozen, the profit over cost is $8 per dozen. The florist can order no more than 60 dozen flowers. Based on previous years, a minimum of 20 dozen carnations must be ordered. The florist cannot order more than $450 worth of roses and carnations. Find out how many dozen of each the florist should order to max. profit! CostTotal ordered Profit xyP=20x + 8y
Sample of what must be handed in for Partner problem