Solving Systems of Equations with Substitution

Warm up: #3

Match the solution to the system of equations.

• (-2, -1)

• 
• (-4, -1)

• 
• (1, 4)

• 
• (2, -1)

• 

Tags

CCSS.8.EE.C.8

Solve the system by substitution.
 
5x + 4y= −14
y =  −7x  −  15 

• (-2, -1)
• (1, -2)
• (-2, 1)
• (-1, -2)

x + 2y = 2
x = -4y + 2

• (-3, 0)
• (0, 2)
• (-3, -2)
• (2, 0)

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

• Run off the graph
• Don't touch
• Intersect
• Exist

x - 3y = -13
4x + 2y = 4

• (1, 4)
• (-1, -4)
• (-1, 4)
• (1, -4)

y = 5x + 1

-10x + 2y = 2

• Infinite solutions

• (0, 0)

• (2, 2)

• (2, 1)

Solve the system of equations.

• (-23, 4)

• (-4, -3)

• (-2, -4)

• No solution

• Infinite solutions

The first step in solving using the substitution method is __________.

• get x by itself
• get y by itself
• get either variable by itself
• add the equations together

What is the first step in solving a system by Substitution?

• Make sure both equations are in standard form.
• Make sure at least one equation is solved for one variable.
• Make sure both equations are in slope-intercept form.
• Make sure both equations can be solved.

Solve the System of Equations (you can use elimination easily for this one!)

y = -2x + 5
y = 2x - 11

• No Solution
• (0, 0)
• (3, -1)
• (4, -3)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6