Elimination Steps

What steps can be taken to isolate the y-value?

2x-4y=-10
2x + 5y =17

*Hint:  isolating y, means eliminating the x-terms

• Multiply the top equation by -2 and add the result equation to the bottom equation.

• Multiply the bottom equation by -1 and add the result to the top equation.

• Multiply the top equation by 5 and the bottom equation by 4 and adding the two equations.

• Multiplying the top equation by 2 and the bottom equation by 2 and adding the resulting equations.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What steps can be taken to isolate the x-terms?

• Multiply the top equation by 3 and add the result to the bottom equation. 

• Multiply the top equation by -3 and add the result to the bottom equation. 

• Multiply the top equation by 5 and the bottom equation by 4 and add the resulting equations.

• Subtract 9 from all terms in the top equation and add the resulting equations.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

• Multiply the top equation by 2 and add the result to the bottom equation.

• Multiply the top equation by -5 and the bottom equation by 4 and add the resulting equations.

• Multiply the top equation by 6 and the bottom equation by 3 and add the resulting equation.

• Multiply the top equation by 3 and add the result to the bottom equation.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

If you are solving a system by elimination and all of the variables cancel leaving you with "0 = -9", what does this tell you about the system?

• The lines intersect at (0. -9). (one solution)

• The lines coincide. (infinitely many solutions)

• The lines are parallel. (no solution)

• The lines intersect two times. (two solutions)

Tags

CCSS.8.EE.C.8B

what is the variable that willl be "eliminated"?

5x - 4y = 11

5x + 4y = -14

• x variable

• y variables

• both variables

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What would be the first step in finding the solution with elimination?

• cross out the 3y and -3y

• cross out the 4x and x

• change all the signs of the second equation

• add 1 and -11

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve for y.

(just the number)

Mathematical Equivalence

ON

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

If you are solving by elimination and all of the variables cancel leaving the equation "0=0", what does that tell you about the system?

• The lines intersect one time. (one solution)

• The lines are parallel. (no solution)

• The lines coincide. (infinitely many solutions)

• The lines intersect two times. (two solutions)

Tags

CCSS.8.EE.C.8B

What is the next step in solving this system by elimination?
2x + 3y = 9
5x + 3y = 21

• Nothing - it is ready to go.

• Multiply one equation by -1

• Multiply the top equation by 3.

• Multiply the bottom equation by 7.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Is this the correct way to multiply the bottom equation by -1?
2x + 3y = 9
-5x - 3y = -21

• Yes

• No

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6