5.3 Substitution Method

Warm up: #1

How many solutions?

• One Solution

• No solution

• Infinitely Many Solutions

Warm up: #2

What is the solution to this system of equations?

• (4, -1)

• (-1, 4)

• (-4, 1)

• (-4, -1)

Warm up: #3

Match the solution to the system of equations.

• (1, 4)

• 
• (2, -1)

• 
• (-2, -1)

• 
• (-4, -1)

• 

Warm up: #4

Which of the following shows the solution to the system?  y= -1/4x + 4 y = 2x + 2

• A

• B

• C

• D

y = -2x + 18
y = 8

• (5, 8)

• (-5, 8)

• (2, 8)

• (-2, 8)

Solve the system by substitution.
 
5x + 4y= −14
y =  −7x  −  15 

• (-2, -1)

• (1, -2)

• (-2, 1)

• (-1, -2)

Solve this system of equations. 
y = 2x + 1
y = 4x - 1

• (1,3)

• (-1,-3)

• (-1,3)

• (3,1)

x + 2y = 2
x = -4y + 2

• (-3, 0)

• (0, 2)

• (-3, -2)

• (2, 0)

Write the new equation to solve after using the substitution process correctly for the system.

y = 5x - 7

-3x - 2y= -12

• -3(5x - 7) - 2y= -12

• -3x - 2(5x-7) = -12

• -3x -2y = 12(5x-7)

Write a new equation after replacing one variable with the other variable in the problem. (Hint: replace the y's).