Elimination Method for Solving Simultaneous Equations
Learn how to solve simultaneous equations by eliminating one variable using addition or subtraction. Letβs get started! π

Video Lesson
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Flashcards
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%20Elimination%20through%20Addition.webp)
%20Elimination%20through%20Transform%20and%20Addition.webp)
%20Elimination%20Through%20Subtraction.webp)
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ποΈ Elimination Method
- The elimination method removes one variable by adding or subtracting two equations.
- The aim is to get an equation like 4x = 12 that is easy to solve.
ποΈ Elimination by Addition
- Add the equations when one variable has opposite signs, like +y and βy.
- That variable cancels out, leaving an equation with one variable.
ποΈ Preparing the Equations
- Transform the equations so one variable can be cancelled, like +3y and β3y.
- Exam tip: when you multiply, multiply every term on both sides of the equation.
ποΈ Elimination by Subtraction
- Subtract the equations when one variable has the same sign, like +2x and +2x.
- This removes that variable so you can solve.
ποΈ Finishing and Checking
- Substitute the value back to find the other variable.
- Exam tip: always check by substituting both x and y into the original equations.
Practice Questions
Test your understanding
Solve the simultaneous equations:
Correct! π +10 pointsNot quite right
Add the two equations together: . This eliminates and simplifies to , so . Substituting into either equation gives , which simplifies to . Therefore, the solution is and .
Solve the simultaneous equations:
Correct! π +10 pointsNot quite right
Add the two equations together: . This simplifies to , so . Substituting into gives , so . Therefore, the solution is and .
Solve the simultaneous equations:
Correct! π +20 pointsNot quite right
Add the two equations together: . This eliminates and simplifies to , so . Substituting into gives , which simplifies to and . Therefore, the solution is and .
Solve the simultaneous equations:
Correct! π +20 pointsNot quite right
Subtract the second equation from the first: . This simplifies to , so . Substituting into gives , which simplifies to . Therefore, the solution is and .
Solve the simultaneous equations:
Correct! π +20 pointsNot quite right
Subtract the first equation from the second: . This eliminates and simplifies to , so . Substituting into gives , which simplifies to and . Therefore, the solution is and .
Solve the simultaneous equations:
Correct! π +30 pointsNot quite right
First multiply the second equation by 2 to align the coefficients of : . Now add this to the first equation: . This simplifies to , so . Substituting into gives , which simplifies to and . Therefore, the solution is and .
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Interactive Activity
Solve simultaneous equations step-by-step using the elimination method
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