7.4-7.5 Solving Systems Using Elimination

• (1, 4)

• (4, 1)

• (1, -4)

• (-4, 1)

• (-3, 2)

• (3, 2)

• (-2, 3)

• (2, -3)

Solve the linear system using elimination.
-9x-4y=-20
5x+4y=4

• (-4,4)
• (4,4)
• (4,-4)
• (-4,-4)

Solve the linear system using elimination.
4x+4y=4
3x+4y=10

• (7,-6)
• (-6,7)
• (6,7)
• (7,6)

To eliminate a variable in the system, should you add the equations or subtract the equations?

x + y = 11

2x + y = 19

• add

• subtract

• neither

• (4, 11)

• (1, -2)

• (5, -12)

• (2, -8)

Solve the linear system using elimination.

x + y = 2

-3x + 4y = 15

• (5, -3)

• (-1, 3)

• (-5, 0)

Solve the linear system using elimination.
-6x+y= -2
-3x-6y= 12

• (2,0)
• (2, 1)

• (0,-2)
• (1, 2)

Solve the linear system using elimination.

5x + 16y = -16
-9x - 8y = 8

• (3, 1)
• (3, -1)
• (-3, -1)
• (0, -1)

On Monday Joe bought 10 cups of coffee and 5 doughnuts for his office at the cost of $16.50.   On Tuesday he bought 5 cups of coffee and 10 doughnuts for a total of $14.25.  Which equations could be used to determine the cost of the coffee? 

• 10c + 5d = 14.25
  5c + 10d = 16.50
• 10c + 5d = 16.50
  5c + 10d = 14.25
• c + d = 10
  5c + 10d = 16.50
• c + d = 5
  5c + 10d = 16.50