Solving pairs of linear equations in two variables

What is your first step?

3x + y = 19

2x - y = 6

• Add

• Multiply by negative 1, then add

What is the best method to use?

4x + 8y = 20

−4x + 2y = −30

• Graphing

• Substitution because one equation is solved.

• Elimination because the equations are in standard form

The coefficients of the eliminated variable must be _____.

• the same number opposite signs (opposites)

• exactly the same

• completely different

• doesn't matter

Solve the system of equations.

5x+6y= -10

3x-2y= -6

• (-2,0)

• (0,-2)

• (2,0)

• (0,2)

Solve the system by elimination:
 $7x-y=10$  
 $-7x+y=-14$  

• (0, -4)

• (2, 4)

• No solution 

• (2, 0)

-8x - 7y = 10
-8x + 5y = 34
answers in (x,y)

• No Solution
• (-3, -10)
• (3, 2)
• (-3, 2)

Solve by elimination:
-x+2y=17

2x+2y=-10

• ARN
• (-9,4)
• (-9,-4)
• (9,-4)

Solve the system of equations using elimination.

 $-7x+4y=-9$  

 $-7x-4y=23$  

• (-4,-1)

• (-1,-4)

• no solution

• infinite solutions

Solve the system:

x + 6y = 17

-x + 3y = -8