Solving Systems of Equations Choose the Best Method

Erin is 3 years younger than twice Alex's age. Their ages combined are 33 years. How old are Alex and Erin. If x=Erin's age and y=Alex's age, choose the system that matches the situation.

• x + y = 33
  y = 2x - 3

• x + y = 33
  x = 2y - 3

• x + y = 33
  x = 3 - 2y

• x + y = 3
  x = 33 - 2y

When using any of the 3 methods to solve a system of linear equations the resulting solution is the same no matter which method is used.

• True; using any method will result in the correct solution.

• False; the solution varies because the solution depends on which method is used.

Identify which method for solving systems is being described by this fact:

The intersection point of the two lines is an ordered pair (x, y) and determines the value of the solution to the system of equations.

• Graphing

• Substitution

• Elimination

Identify which method for solving systems is being described by this fact:
If one equation is isolated like y = 2x or x = 7 - 4y then this method should be used.

• Graphing

• Substitution

• Elimination

Identify which method for solving systems is being described by this fact: Equations must have like terms "stacked" up vertically, usually written in standard form.

• Graphing

• Substitution

• Elimination

If the solution to a system of equations is the point (3, 5.25), which method of solving the system would be the WORST choice?

• Graphing

• Substitution

• Elimination

• All Methods Would Be Good Choices

Which variable would be the EASIEST to isolate for the substitution method in the system?

• X in the first equation

• Y in the first equation

• X in the second equation

• Y in the second equation

Which variable would be the BEST choice to isolate for the substitution method in the system?

• X in the first equation

• Y in the first equation

• X in the second equation

• Y in the second equation

• Substitution

• Elimination

Which method would require the LEAST amount of work to solve the system?

• Substitution

• Elimination