Systems of Equations What does it mean to substitute something for another? NEXT
Combination Plate 1 cheese enchilada 1 beef taco 1 chalupa $6.75 Queso Plate 1 cheese enchilada 1 chile con queso 1 tamale $6.25 Fajita Plate Chicken or beef fajitas 1 chile con queso $7.75 San Antonio Plate 1 quesadilla 1 chile con queso 1 taco $7.50 Los Amigos Plate 2 cheese enchiladas 2 tacos guacamole $7.25 All lunches served with rice and beans. Sorry, no substitutions!
Solving without the Cards Using the same two equations: and. NEXT
We modeled the equation 3x + 4y = 24. 3x + 4y = 24 NEXT
We substituted 2x – 5 for each y in the equation. 2x – 5 3x + 4y = 24 3x + 4(2x – 5) = 24 NEXT
2x – 5 We simplified the left side of the equation. 3 xs plus 4 sets of 2x 3x + 4(2x) 3x + 8x 11x 4 sets of –5 4(–5) –20 AND 11x – 20 = 24 3x + 4y = 24 3x + 4(2x – 5) = 24 3x + 8x – 20 = 24 11x – 20 = 24 NEXT
We solved the equation to determine the value of x. NEXT
We returned to the original model of 3x + 4y = 24. 3x + 4y = 24 NEXT
3x + 4y = 24 We substituted 4 in place of each x in the equation (4) + 4y = 24 NEXT
3x + 4y = (4) + 4y = 24 NEXT We simplified the left side of the equation. 4 y’s 4y 3 sets of 4 3(4) 12 AND y = 24
We solved the equation to determine the value of y. NEXT
What is the solution? The solution to the system of equations is What does this mean? NEXT
Solve the system by graphing. NEXT The values x = 4 and y = 3 satisfy both equations.
Substitute the expression that is equal to the circled variable in the other equation. Solve an equation for one variable. Simplify and solve. Substitute the value found into the equation that was solved for the circled variable. Simplify and solve. Write the solution. yes no Notes Is one equation solved for one of the variables? Circle the isolated variable.