 # Solving a system of equations by SUBSTITUTION

## Presentation on theme: "Solving a system of equations by SUBSTITUTION"— Presentation transcript:

Solving a system of equations by SUBSTITUTION
Step 1: Solve an equation for one variable. Pick the easier equation. The goal is to get y= ; x= ; a= ; etc. Step 2: Substitute Put the equation solved in Step 1 into the other equation. Step 3: Solve the equation. Get the variable by itself. Step 4: Plug back in to find the other variable. Substitute the value of the variable into the equation. Step 5: Check your solution. Substitute your ordered pair into BOTH equations.

1) Solve the system using substitution
x + y = 5 y = 3 + x Step 1: Solve an equation for one variable. The second equation is already solved for y! Step 2: Substitute x + y = 5 x + (3 + x) = 5 2x + 3 = 5 2x = 2 x = 1 Step 3: Solve the equation.

1) Solve the system using substitution
x + y = 5 y = 3 + x x + y = 5 (1) + y = 5 y = 4 Step 4: Plug back in to find the other variable. (1, 4) (1) + (4) = 5 (4) = 3 + (1) Step 5: Check your solution. The solution is (1, 4). What do you think the answer would be if you graphed the two equations?

Solve the system using substitution
3x – y = 4 x = 4y - 17

Solving a system of equations by SUBSTITUTION
Pick the easier equation. The goal is to get y= ; x= ; a Step 1: Pick the easier equation. The goal is to get y= ; x= ; a= ; etc. . Put the equation solved in Step 1 into the other equation Using the equation solved in Step 1 replace the variable in the other equation. Therefore you have one equation with one variable. Step 2: he variable by itself. ck the easier equation. The goal is to get y= ; x= ; a= ; etc Step 3: Get the variable by itself. . Substitute the value of the variable into the equation. Write your answer as an ordered pair (x, y). Step 4:

REAL WORLD APP You buy a total of 50 burgers and hotdogs for \$90. You pay \$2 per burger and \$1.50 per hotdog. Write a system of equations to find the number of x burgers and y hotdogs.

Solve the system by substitution
_______burgers and ______hotdogs

Try this: You sell lemonade for \$2 per cup and orange juice for \$3 per cup. You sell a total of 100 cups for \$240. Write a system of equations to find the number of x cups of lemonade and y cups of orange juice.

Solve the system by substitution
_______cups lemonade & ______cups orange juice

Download ppt "Solving a system of equations by SUBSTITUTION"

Similar presentations