Solving Systems of Equations by Substitution Review

What is the first step in solving a system by Substitution?

• Make sure both equations are in standard form.

• Make sure at least one equation is solved for one variable.

• Make sure both equations are in slope-intercept form.

• Make sure both equations can be solved.

Solve the system by substitution.

x + 2y = 2

x = -4y + 2

• (-3, 0)

• (0, 2)

• (-3, -2)

• (2, 0)

Solve the system by substitution.

y = -6x + 5

-2x + y = 5

• (-3, -6)

• (-6, 3)

• (0, 5)

• (-3, 5)

Solve the system by substitution.

6x + y = -1

y = -3x - 4

• (3, 1)

• (1, 7)

• (-3, 1)

• (1, -7)

This system has _____ solutions

• 0

• 1

• 2

• Infinitely many

The first step in solving a system of equations using the SUBSTITUTION METHOD is __________.

(Read all the answers before choosing one.)

• get x by itself

• get y by itself

• get EITHER x or y by itself

• add the equations together

Which answer has a correct next step for this system? (Read all three answers carefully before selecting one!)

• The variable is already isolated, so we've already solved the system.

• The variable is already isolated for y, so we substitute it in the second equation like this:

  2(6x) + 5y = 32

• The variable is already isolated for y, so we substitute it in the second equation like this:

  2x + 5(6x) = 32

Use the system of equations below to answer the question. After substituting the first equation into the second one and working it out, I got x = 1. What should I do next?

• Fill in 1 for x in y = 6x

• Fill in 1 for y in y = 6x

• Fill in 1 for y in 2x + 5y = 32

Which answer has a correct next step for this system? (Read all three answers carefully before selecting one!) 3x + 4y = 3 y = 3x + 5

• The variable is already isolated, so we've already solved the system.

• The variable is already isolated for y, so we substitute 3x + 5 in the first equation like this:

  3x + 4(3x + 5) = 3

• The variable is already isolated for y, so we substitute 3x + 5 in the second equation like this:

  3(3x + 5) + 4y = 3

What is the solution to this system?

(Use the substitution method.)

8x - 2y = 6

y = 3x

• (3, 9)

• (5, 2)

• (2, 3)

• (3, 2)