Presentation on theme: "Solving a system of equations by SUBSTITUTION"— Presentation transcript:
1Solving a system of equations by SUBSTITUTION Step 1: Solve an equation for one variable.Pick the easier equation. The goalis to get y= ; x= ; a= ; etc.Step 2: SubstitutePut the equation solved in Step 1into 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 variableinto the equation.Step 5: Check your solution.Substitute your ordered pair intoBOTH equations.
21) Solve the system using substitution x + y = 5y = 3 + xStep 1: Solve an equation for one variable.The second equation isalready solved for y!Step 2: Substitutex + y = 5 x + (3 + x) = 52x + 3 = 52x = 2x = 1Step 3: Solve the equation.
31) Solve the system using substitution x + y = 5y = 3 + xx + y = 5(1) + y = 5y = 4Step 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?
4Solve the system using substitution 3x – y = 4x = 4y - 17
5Solving a system of equations by SUBSTITUTION Pick the easier equation. The goalis to get y= ; x= ; aStep 1:Pick the easier equation. The goalis to get y= ; x= ; a= ; etc..Put the equation solved in Step 1into the other equationUsing 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 goalis to get y= ; x= ; a= ; etcStep 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:
6REAL WORLD APPYou 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.
7Solve the system by substitution _______burgers and ______hotdogs
8Try 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.
9Solve the system by substitution _______cups lemonade & ______cups orange juice