### About Solving Systems by Substitution:

Another alternative to solve a linear system is known as the substitution method. When we use this method we solve one equation for one of the variables. We then plug in for that variable in the other equation. From this, we can obtain the solution to the system.

Test Objectives
• Demonstrate an understanding of a system of linear equations
• Demonstrate the ability to solve a system of linear equations by substitution
• Demonstrate the ability to check the solution for a system of linear equations
Solving Systems by Substitution Practice Test:

#1:

Instructions: Solve each linear system by substitution.

a) 3x - 4y = -18 : -x + y = 4

b) -4x - 4y = 4 : y = -4

#2:

Instructions: Solve each linear system by substitution.

a) 2x - y = -6 : x - 2y = -9

b) -7x - 8y = 13 : -x + y = 4

#3:

Instructions: Solve each linear system by substitution.

a) 2x + 4y = 14 : 6x - 8y = -18

b) 6x - 3y = 9 : -2x - 2y = -6

#4:

Instructions: Solve each linear system by substitution.

a) 4x + 6y = -6 : 12x + 18y = -8

b) 2x + 3y = 8 : 3x + 3y = 3

#5:

Instructions: Solve each linear system by substitution.

a) -3x - 4y = -6 : -2x + 2y = -4

b) 2x - y = -12 : -8x - 2y = 12

Written Solutions:

#1:

Solutions:

a) (2,6)

b) (3,-4)

#2:

Solutions:

a) (-1,4)

b) (-3,1)

#3:

Solutions:

a) (1,3)

b) (2,1)

#4:

Solutions:

a) no solution

b) (-5,6)

#5:

Solutions:

a) (2,0)

b) (-3,6)