Solving Linear Equations with the Elimination Method

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12 Questions

What is the primary purpose of using the elimination method in solving systems of linear equations?

To simplify the problem by eliminating one variable

When setting up a system of two linear equations in two variables, what should be ensured about the coefficients or constant terms to apply the elimination method effectively?

They should not all be zero

Which approach is used in the elimination method to make one coefficient zero while keeping the other non-zero?

Eliminating by adding

When using the elimination method and adding equations, what can be said about the coefficient of the variable being eliminated?

It becomes zero

What is the key consideration when choosing coefficients or constants to eliminate in the elimination method?

Having them not equal zero

After performing elimination by adding, what is the next step in solving for one of the variables?

Dividing both sides by a specific coefficient

What is a key advantage of using the elimination method for solving systems of linear equations?

It can identify special cases like inconsistent or dependent systems

When using the elimination method, why might we multiply one equation by a constant factor?

To make one coefficient of x or y zero

What does it mean when a system of linear equations results in an equation that is always false after applying the elimination method?

The system has no solutions

In the elimination method, after solving for one variable, what is the next step to find the remaining variable?

Substitute the value back into one of the original equations

What type of system of linear equations would lead to having an equation that is always true after applying the elimination method?

Dependent system

Why is the elimination method considered a powerful tool for solving systems of linear equations?

It is versatile and efficient for various types of systems

Study Notes

Solving Linear Equations in Two Variables with the Elimination Method

When graphing or finding the solutions to systems of linear equations in two variables, the elimination method is a powerful technique that helps to simplify the problem. This strategy involves manipulating the equations to eliminate one variable, making it easier to solve for the other.

Setting up the equations

Suppose we have a system of two linear equations in two variables, (x) and (y), such as:

[ a_1x + b_1y = c_1 ]

[ a_2x + b_2y = c_2 ]

Choosing a strategy for elimination

To begin, we'll choose one of the equations as our base and identify which coefficient or constant term should be eliminated. The key here is to choose coefficients or constants that are not zero, so we can perform the necessary operations without divididing by zero.

Eliminating one variable

There are two primary approaches for eliminating one variable:

  1. Eliminating by adding: We can add or subtract the two equations to make one coefficient of (x) or (y) zero, while keeping the other non-zero. Let's say we add (a_2) times the first equation to the second equation, such that:

[ (a_2a_1 + b_2)x + (a_2b_1)y = c_2 + a_2c_1 ]

Now we can solve for (y) (assuming (a_2b_1 \neq 0)) by dividing both sides by (a_2b_1):

[ y = \dfrac{1}{a_2b_1}(c_2 + a_2c_1 - a_2a_1x) ]

  1. Eliminating by multiplying: We can multiply one of the equations by a constant factor to make one coefficient of (x) or (y) zero, while keeping the other non-zero. Let's say we multiply the first equation by (-b_2) and add it to the second equation:

[ (-b_2a_1 + b_1b_2)x + (b_2b_1)y = -b_2c_1 + b_1c_2 ]

Now we can solve for (y) (assuming (b_2b_1 \neq 0)) by dividing both sides by (b_2b_1):

[ y = \dfrac{1}{b_2b_1}(b_1c_2 - b_2c_1 - b_2a_1x) ]

Solving for the remaining variable

After eliminating one variable, we'll have an equation involving only one of the variables, which we can solve for that variable. Then we can substitute this value back into one of the original equations to find the other variable.

Special cases

The elimination method works best when the system has a unique solution. However, it can also be used to identify special cases such as:

  1. Inconsistent system: The system has no solutions, and the elimination method will result in an equation that is always false.
  2. Dependent system: The system has infinitely many solutions, and the elimination method will result in an equation that is always true.
  3. Identical equations: The system represents the same line, and the elimination method will result in an equation that is always true or false, depending on the initial strategy.

Conclusion

The elimination method is a powerful tool for solving systems of linear equations in two variables. While there are other techniques, such as substitution and elimination by graphing, elimination is a straightforward and efficient method that can be applied to a wide variety of systems. With practice, you'll find that the elimination method becomes a quick and reliable strategy for solving these types of equations.

Learn how to solve systems of linear equations in two variables using the elimination method. This technique involves manipulating equations to eliminate one variable, making it easier to find the solutions. Explore strategies for elimination, different approaches, and special cases that can arise when using this method.

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