Solving Systems of Equations by Substitution and Graphing

What is the best method to use?

y = −3x + 5

y = x -1

• Graphing, because they are both in slope-intercept form

• Substitution because a variable is isolated (solved for)

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

Solve the system:
2x - 5y = 12
y = -2

• y = -2

• (11, -2)

• (1, -2)

• no solution

7x - y = -10
-7x + 5y = -6

• (-2, -4)

• (-2, -1)

• (-4, -1)

• (6, -8)

The cost of 5 squash and 2 zucchini is $1.32. Three squash and 1 zucchini cost $0.75. Write a system of equations.

• 5q + 2z = 1.32
  1z = 0.75

• 5q + 2z = 1.32
  3q + 1z = 0.75

• q + z = 1.32
  q + z = 0.75

• 5q + 2z = 0.75
  3q + 1z = 1.32

y = -3x + 11 5x + y = 21

• (1, -5)

• (1, 5)

• (-4, 5)

• (5, -4)

x - 3y = -13

4x + 2y = 4

• (1, 4)

• (-1, -4)

• (-1, 4)

• (1, -4)

−3x − 3y = 3
y = −5x − 17 

• (-4,3)

• (4,-3)

• (3,-4)

• (-3,-4)