Solve Systems Using Substitution When Variable Is Isolated

Which answer has a correct first step for this system:

3x + 3y = 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 it in the first equation and solve for x

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

• Free sha vaca doo

• The variable is already isolated for y, so we substitute it in the second equation and solve for x

  y = 3(3x + 3y) = 3

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.

• -4x + 3(4x - 11) = -1

• -4(4x - 11) + 3y = -1

• -4x + 3y = 4x - 11

Solve the following systems of equations using substitution:

x = 6

y = 2x - 3

• (6, 6)

• (6, 9)

• (9, 6)

• (9, 9)

Solve the following systems of equations using substitution:

5x - 2y = 3

y = 2x

• (6, 3)

• (1, 2)

• (3, 6)

• (2, 1)

Solve the following systems of equations using substitution:

y = 3 - x

3y + x = 5

• No solution

• (1, 2)

• (3, 0)

• (2, 1)

Solve this system using substitution

y = 3x - 5

2x + 4y = -6

• (1, -2)

• (2, -2)

• (1, 2)

• Why have you done this?

Solve the system of equations by substitution.
y = -4x + 5
y =  3x - 16

• (-3, -25)
• (3,-7)
• (11, 17)
• (21, 47)

y = -6
-3x - 6y = 24

• (6, 6)
• (6, -6)
• (4, -6)
• (-6, 4)