FTCE General Knowledge Math Practice Test

Which method would you use to solve for a variable by replacing it in an equation?

1. Elimination method

2. Combination method

3. Substitution method

4. Graphical method

The correct answer is: Substitution method

The substitution method is a technique used to solve equations where one variable can be expressed in terms of another. This method involves isolating one variable in one of the equations, then substituting that expression into another equation to find the value of the second variable. For example, if you have two equations, you might start with one equation that you can rearrange to solve for one variable. Once you have that variable expressed in terms of the other, you plug it into the second equation. This allows you to solve for the remaining variable without needing to manipulate the equations concurrently, as you would in elimination methods. In contrast, the elimination method focuses on adding or subtracting equations to eliminate a variable, while the graphical method involves plotting equations on a graph to find their intersection points. The combination method could refer to various approaches but is not a standard term in solving for variables in equations. Thus, the substitution method clearly stands out as the correct choice for solving for a variable by replacing it in an equation.