I can solve systems of equations by substitution

I can solve systems of equations by substitution Warm Up

I can solve systems of equations by substitution Warm Up

I can solve systems of equations by substitution Warm Up

I can solve systems of equations by substitution Warm Up Write a system of equations: Sara has 16 baseball cards and buys 7 more each week. Ted has 2 baseball cards and collects 9 more each week. Write a systems of equations and solve to find out when they will have the same number of cards.

Homework Questions

Diamond Problems xy x y x+y 4 -8

Diamond Problems -42 xy x y x+y 3 -14 -11

Diamond Problems xy x y x+y -64 16 12 -4

Solve by Graphing • The solution isn’t at a clear point!

Try it! • Try problems 1 and 2 on your practice sheet using the method we just discovered. See if you can solve the systems

Solving Systems with Substitution Steps 1. Determine variable to substitution 2. Make substitution 3. Solve •

Solving Systems with Substitution Steps 4. Plug back into an original equation 5. Solve for missing variable 6. Write answer as a point •

Practice 20 minutes Check your answers on the back table

Writing and Solving Systems April sold 75 tickets to a school play and collected a total of $495. If the adult tickets cost $8 each and child tickets cost $5 each, how many adult tickets and how many child tickets did she sell?

April sold 75 tickets to a school play and collected a total of $495. If the adult tickets cost $8 each and child tickets cost $5 each, how many adult tickets and how many child tickets did she sell? Define variables: a = the number of adult tickets. c = the number of child tickets. System of equations: a + c = 75 8 a + 5 c = 495 State your solution(s): There were 40 adult tickets and 35 child tickets sold. 40 + 35 = 75 8(40) + 5(35) = 495 320 + 175 = 495 Solve a + c = 75 8 a + 5 c = 495 a = 75 – c 8(75 – c) + 5 c = 495 600 – 8 c + 5 c = 495 600 - 3 c = 495 105 = 3 c 35 = c a + c = 75 a + 35 = 75 a = 40

Writing and Solving Systems At a baseball game, Jose bought four hot dogs and one soda for $12. At the same time, Allison bought two hot dogs and four sodas for $13. Find the cost of one hot dog and one soda.

At a baseball game, Jose bought four hot dogs and one soda for $12. At the same time, Allison bought two hot dogs and four sodas for $13. Find the cost of one hot dog and one soda. Define variables: h = the price of hot dog. s = the price of a soda. System of equations: 4 h + s = 12 2 h + 4 s = 13 State your solution(s): A hot dog costs $2. 50 and a soda costs $2. 00. 4(2. 5) + 2 = 12 2(2. 5) + 4(2) = 13 5 + 8 = 13 Solve 4 h + s = 12 2 h + 4 s = 13 s = 12 – 4 h 2 h + 4(12 – 4 h) = 13 2 h + 48 – 16 h = 13 48 – 14 h = 13 35 = 14 h 2. 5 = h 4 h + s = 12 4(2. 5) + s = 12 10 + s = 12 s = 2

Homework Textbook