Systems Elimination Opposite Terms

What variable do you eliminate?

4x + 8y = 20

−4x + 2y = −30

• X because they have opposite signs

• Y because they have opposite signs

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

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

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

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

• (-1,2)

• (5,4)

• (4,5)

• (2,-1)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system:

x+ 3y = 9

2x+ y = −2

• (3,2)

• (-2, 2)

• (3, -4)

• (-3, 4)

• (0.5, -3)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system:

y= 3x -13

2x +4y =4

• (5,2)

• (4, -1)

• (-4, -1)

• (5, -2)

• (-4, 1)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What is the first step in solving a system of equations by elimination/matrices?

• Get both equations in standard form and line up the like terms.

• Get both equations in slope-intercept form.

• Get both equations equal to zero.

• Put the x terms first.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

-3x+3y = 18
5x-3y = -26
answers in (x,y)

• (4,2)

• (-4,-2)

• (-4,2)

• (4,-2)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve using elimination. 
−4x − 4y = 0
4x + 4y = 0 

• (−6, −4) 

• Infinite number of solutions  

• (−6, 10) 

• (6, 4) 

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What is the proper way to set up the equation to begin solving?

y = 6x − 11

−2x − 3y = −7

• -2(-11) -3y= -7

• -2(6x-11) -3y = -7

• -2x -3(11) = -7

• -2x - 3(6x-11)= -7

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

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

• Run off the graph

• Don't touch

• Intersect

• Exist

Tags

CCSS.8.EE.C.8B