Systems of Equations

What is the best method to use?

y = −3x + 5

5x − 4y = −3

• Graphing

• Substitution because a variable is defined

• Elimination because the equations are in standard form

Solve for x and y
5x + 3y = 7
y = 4

• (4,1)
• (4,-1)
• (1,4)
• (-1,4)

What variable do you eliminate?

4x + 8y = 20

−4x + 2y = −30

• X because they have opposite signs

• Y because they have opposite signs

Steffen graphed two lines in order to find the solution to a given system of equations.
What is the solution?

• (-3,-8)
• (-8,-3)
• (3,-8)
• (8,3)

Solve for x and y
3x + 2y = 16
7x + y = 19

• (-2,5)
• (-2,-5)
• (2,-5)
• (2,5)

What is the best method to use?

−4x − 2y = −12

4x + 8y = −24

• Graphing

• Substitution because a variable is defined

• Elimination because the equations are in standard form.

Solve the system:

y= 3x -13

2x +4y =4

• (5,2)

• (4, -1)

• (-4, -1)

• (5, -2)

• (-4, 1)

What is the best method to use?

2x − 3y = −1

y =x − 1

• Graphing

• Substitution because a variable is defined

• Elimination because the equations are in standard form.

When you graph the exact same equation twice,

• you will have no solution. 
• you will have one solution.
• you will have infinite solutions. 
• you will graph a giraffe. 

Solve the system:

y=5x−5

y= −4x+22

• (1, 2)

• (3, 10)

• (-1, 2)

• (-3, 10)