Intro to Substitution Method

Multiple Choice

The solution (x, y) to a system of equations is the point where they...? 

• Run off the graph

• Don't touch

• Intersect/Cross

Match

Warm up: #3

Match the solution to the system of equations.

(-2, -1)

(2, -1)

(1, 4)

(-4, -1)

• (-2, -1)

• (2, -1)

• (1, 4)

• (-4, -1)

Multiple Choice

Does this have a solution?

• Yes- one solution

• No solution
• Yes - Infinitely Many Solutions

Steps for Solving Systems with Substitution

Step 1: Solve 1 equation for 1 of the variables.

x=___ or y=____​

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Step 2:​ Substitute x =___ or y = ___ from the first step into the other equation and solve for the variable.

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​Step 3: Substitute your answer into one of the original equations and solve for the other variable.

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Step 4: Write your answer as an ordered pair.​

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​Write what I write.

Multiple Choice

If our system of equation is y = 3x and y = 4x + 3, we can substitute the first equation into the second. What do we get when we do that?

• y = 3x + 4x + 3

• 3x = 4x + 3 

• y = x + 3

• 4x + 3

Multiple Choice

If our system of equation is y = 5x - 5 and y = 14x, we can substitute the second equation into the first. What do we get when we do that?

• y = 5x - 5 + 14x 

• 5x - 5 - 14x

• 5x - 5 = 14x

Multiple Choice

Solve this system of equations:

y = -2x + 18
y = 8

• (5, 8)

• (-5, 8)

• (2, 8)

• (-2, 8)

Multiple Choice

Solve this system of equations. 
y = 2x + 1
y = 4x - 1

• (1, 3)

• (-1, -3)

• (-1, 3)

• (3, 1)