ByStanley Brown

&Rodney Lewis

It is a extension of the elimination method is to multiply one or both equations in a system by some number so that adding or subtracting eliminates a variable.

Need to know how to do basic elimination Example: 3x-2y=5

-3x+4y=6http://www.coolmath.com/algebra/12-2x2-systems-

of-equations/03-solving-by-elimination-addition-01.htm

Need to know how to solve multi step equations using multiplication and division

http://www.coolmath.com/algebra/06-solving-equations/index.html

3x+4y=-25 Multiply by 2(+) 2x-3y=6 Multiply by -3

6x+8y=-50 -6x+9y=-18

17y = -68 17 17

y=-4

Multiply so that the “X” coefficients are Additive inverses.

Add the equations, The inverses will cancel leaving “Y” by itself

Divide by 17 to find the value of your “Y”

Your “Y” will be -4

2x-3y=62X-3(-4)=6

2x+12=6

2x+12=6 -12 -12

2x=-62 2

X=-3

To find your X you have to substitute Y back into one of the equations. Y=-4

Multiply -4 by -3

Subtract 12 from both sides of the equations.

Divide each said by 2

X will equal -3 Your final solution

will be (-3,-4)

1st Choose one equation and solve for x or y Solve for y in the 2nd equation.Multiply by -2 -6x-4y=-20Multiply by 3 (+) 6x-3y=27

2nd Eliminate Cancels your x value -6x-4y=-20

(+)6x-3y=27 3rd solveDivide -7y=7 Y=-1

7

4Th Substitute the value found in step 2 back into one of the equations and solve.Your Y value was equal to -1 6x-3(-1) =27 Subtract 3 from each side 6x+3=27

-3 -3 Divide 6 from each side 6x=24 x=4

6Your solution will be (4,-1)

1. 2x-y=63x+4y=-2

2. 2x+7y=1x+5y=2

3. 4x+7y=66x+5y=20

4. x+y=32x-3y=16

5. 2x+y=53x-2y=4

6. 8x-3y=-112x-5y=27

7. 4x-7y=103x+2y=-7

8. 12x-3y=-36x+y=1

9. 1.8x-0.3y=14.4x-0.6y=2.8

10. 3x-½y=105x+¼y=8

Elimination with multiplication http://www.coolmath.com/algebra/12-2x2-syste

ms-of-equations/03-solving-by-elimination-addition-02.htm

fun way to practice with regular equations http://www.coolmath-games.com/0-

arithmeticgame/index.htmlKnow enough? Try the test http://www.glencoe.com/sec/math/studytools/cgi-bin/

msgQuiz.php4?isbn=0-07-860390-0&chapter=7&lesson=4&headerFile=6&state=na

1. (5,-1)2. (4,-1)3. (5,-2)4. (5,-2)5. (2,1)6. (-4,-7)7. (-1,-2)8. (0,1)9. (10,12)10. (2,-8)