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# Elimination strategies

Practice identifying strategies for eliminating variables in a system of equations.

## Want to join the conversation?

• Also could you simplify the equations first?
• Yes,It can be simplified if all the terms in the equation are having a common factor.
For example-
4x - 2y = 8 can be simplified to 2x - y = 4
(By dividing by 2 because, 2 is their common factor)
• Could dividing the equations work?
• Determine the multiplier of the variable and divide both sides by it. Because the equation involves multiplying 20x, undo the multiplication in the equation by doing the opposite of multiplication, which is division. Divide each side by 20.
Reduce both sides of the equal sign. 20x ÷ 20 = x. 170 ÷ 20 = 8.5. x = 8.5.
• So, as long as you eliminate a variable, you can proceed to solving the equation?
• In the elimination method you either add or subtract the equations to get an equation in one variable. When the coefficients of one variable are opposites you add the equations to eliminate a variable and when the coefficients of one variable are equal you subtract the equations to eliminate a variable.
Set apart two of the equations and eliminate one variable. Set apart another two equations and eliminate the same variable. Repeat the elimination process with your two new equations. Solve the final equation for the variable that remains.
• I still dont know how to do this
• At , why did Sal rule Choice A after the x's and the y's don't get eliminated? Wouldn't Sal subtract the numbers on the right side (7-7=0)? This would eliminate the variable on the right side!
• The numbers on the right are constants, as are the numbers in front of X and Y.

The variables are Xs and Ys themselves. They're called variables because we do not know their value - which can change or vary, depending on the situation/problem/question.
• how do you solve -3x Multiplied by Y
• If you multiply -3x * y, you get the answer of -3xy. This is one of the rules of multiplying by variables. The terms must combine because they are being multiplied, and a negative times a positive is equal to a negative.

Hope this helps! -`Johnny Unidas`
• So it's possible to just do one thing to one equation and not the other? That seems wrong somehow. Wouldn't that mess the whole thing up?
• Equations are independent of each other, so you do not have to do the same thing to all the equations. You still have to live with the rule of a single equation that if you do something to one side, you have to do the same thing to the other to keep it balanced.
(1 vote)
• can you multipy everything first?