Module 6 End-Chapter Practice 8th Grade

What operation is used to ELIMINATE a variable?

• addition

• subtraction

• multiplication

• division

The coefficients of the eliminated variable must be _____.

• oppoistes

• the same

• distinct

• does not matter

What operation is used to manipulate equation to have OPPOSITE coefficients?

• addition

• subtraction

• multiplication

• division

To get opposite coefficients, multiply ____.

• left side of =

• right side of =

• only the coefficients eliminating

• everything

To find the second variable, substitute into ____.

• an original equation

• a manipulated equation

• the top equation, always

• whatever is the easiest

Order the algorithm (steps) to elimination

• Solve for variable

• Determine the variable to eliminate

• add vertically

• multiply equation(s) to have opposite coefficients

• Align like terms vertically

Solve the system of equations using elimination.

 $-7x+4y=-9$  

 $-7x-4y=23$  

• (-4,-1)

• (-1,-4)

• no solution

• infinite solutions

Solve the system of equations by elimination.
 $3x-3y=4$  

 $-3x+3y=3$  

•  $0\ne7$ no solution

• (0,0)

• (0,7)

• (7,0)