Solving by Elimination
Grade 8 · Math · Systems of Equations · Prince Edward Island, Canada
Lesson Summary
Solve a system by adding or subtracting equations to eliminate one variable.
Explanation
The elimination method works by adding or subtracting the two equations so that one variable cancels out. Sometimes you need to multiply one or both equations by a number first so the coefficients match up. Once a variable is eliminated, solve for the remaining one, then substitute back. This method is especially useful when neither equation is already solved for a single variable.
Practice Questions
Q1: Solve: x + y = 10 and x − y = 4.
Answer: Add the equations: 2x = 14, so x = 7. Then 7 + y = 10, so y = 3. Solution: (7, 3).
Q2: Solve: 2x + 3y = 12 and 2x + y = 8.
Answer: Subtract the second from the first: 2y = 4, so y = 2. Then 2x + 2 = 8, 2x = 6, x = 3. Solution: (3, 2).
Q3: Why would you multiply an equation before adding?
Answer: To make the coefficients of one variable the same size so they cancel when you add or subtract the equations.
People Also Ask
What is Solving by Elimination in Grade 8 Math?+
Solving by Elimination is a lesson in the Systems of Equations chapter of Grade 8 Math. It is part of the Prince Edward Island, Canada school curriculum and covers key concepts that students need to understand at this level.
What grade level covers Solving by Elimination?+
Solving by Elimination is taught in Grade 8 as part of the Math curriculum in Prince Edward Island, Canada.
How can I help my child with Systems of Equations in Math?+
Start with the lesson summary and explanation on this page. Practice the questions provided, then use TutorTom for personalized, step-by-step help with Systems of Equations topics.