Solving Systems of Equations by Graphing, Substitution and Elimination

What variable do you eliminate?

4x + 8y = 20

−4x + 2y = −30

• X because they have opposite signs

• Y because they have opposite signs

What is the proper set up to solve the equation?

• -7(11) -2y = -13

• -7(2y +11)-2y = -13

• -7x -2(11) =-13

• -7x - 2(2y+11)= -13

What variable do you eliminate, and what do you multiply the equation(s) by?

• You eliminate x, and multiply the top equation by -2

• You eliminate y, and multiply the top equation by 7

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

• (4,1)

• (4,-1)

• (1,4)

• (-1,4)

Solve the system given:
3x - y = 7
2x + y = 3

• (-1,2)

• (5,4)

• (4,5)

• (2,-1)

Solve the system:

y= 3x -13

2x +4y =4

• (5,2)

• (4, -1)

• (-4, -1)

• (5, -2)

• (-4, 1)

Solve the system:

x+ 3y = 9

2x+ y = −2

• (3,2)

• (-2, 2)

• (3, -4)

• (-3, 4)

• (0.5, -3)

Solve the system:
x + y = 19
y = 3x - 1

• (14, 5)

• (11, 8)

• (5, 14)

• (8, 11)

Solve the system:
3x + y = 19
2x - y = 6

• (5, 14)

• (4, 5)

• (5, 4)

• (14, 5)

Which method would be best (quickest) for solving the system below:
3x - 4y = -2
y = 2x + 1

• Substitution

• Elimination

• Graphing

• None