Solving Systems of Equations with the Substitution Method

Why is the substitution method used instead of graphing in some cases?

• It is faster than graphing.

• It is more accurate when solutions are not integers.

• It requires less paper.

• It is easier to understand.

What is the first step in the substitution method?

• Add the equations together.

• Graph the equations.

• Solve for a variable in one of the equations.

• Multiply both equations by a constant.

In the first example, what is the value of y when x = 2y and 7y - x = 15?

• 2

• 3

• 4

• 5

What is the final solution for the system x = 2y and 7y - x = 15?

• (7, 2)

• (6, 3)

• (2, 7)

• (3, 6)

In the second example, what is the value of x when y = -4x + 8 and y = x + 7?

• 0.2

• 0.5

• 1.2

• 1.5

What is the final solution for the system y = -4x + 8 and y = x + 7?

• (7.2, 0.2)

• (7.5, 0.5)

• (0.5, 7.5)

• (0.2, 7.2)

In the third example, what is the value of x when 3y + 2x = 4 and -6x + y = -7?

• 1.75

• 2.0

• 1.5

• 1.25

What is the final solution for the system 3y + 2x = 4 and -6x + y = -7?

• (1.25, 0.5)

• (0.5, 1.25)

• (0.75, 1.5)

• (1.5, 0.75)

In the practice problem, what is the value of y when x = 2.5 and y = 1.75?

• 1.5

• 1.75

• 2.5

• 2.0

What is the final solution for the practice problem where x = 2.5 and y = 1.75?

• (2.5, 1.75)

• (1.75, 2.5)

• (2.0, 1.5)

• (1.5, 2.0)