Solving Systems by Elimination

Solve the system by elimination.  

−8x − 10y = 20
−8x − 6y = −4 

• Infinite number of solutions  

• (6, 5) 

• (−6, −5) 

• (5, −6) 

Solve by elimination 2x+9y= -7 6x-3y= 9

• (-1, -1)

• (2,-1)

• (1,1)

• (1,-1)

• (-1,2)

What is the resulting combined equation for the system below?

• -18x = 18

• y = 18

• 2y= 18

• 18x + 2y = 18

Work Must be shown:

Solve the system by elimination.   −8x − 10y = 20 −8x − 6y = −4 

• Infinite number of solutions  

• (6, 5) 

• (−6, −5) 

• (5, −6) 

7x - y = 10

-7x + y = -14

• No Solution

• (4, 1)

• Infinitely Many Solutions

• (2, -4)

Answer explanation

7x - y = 10

-7x + y = -14

All of the like terms have opposite coefficients, so both variables will be eliminated when we add the equations together. We cannot eliminate one without the other.

We are left with:

0=-4

This is a contradiction (false), so there is NO SOLUTION.

Work Must be shown:

Solve the system by elimination.   −8x − 10y = 20 −8x − 6y = −4 

• Infinite number of solutions  

• (6, 5) 

• (−6, −5) 

• (5, −6) 

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

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

• (4,2)

• (-4,-2)

• (-4,2)

• (4,-2)

What is the solution?

• (1, -2)

• (-2, 1)

• (-4, 1)

• (2, 1)

Solve by elimination

4x-6y= -6

-2x-12y= -12

• (0,1)

• (1,0)

• (1,1)

• (0, 2)