Solve by elimination math help

Question

-9+5y=-4x

-11x=-20+9y

Answer 1

This is Elimination Method.

first bring like terms together starting:

 

-9+5y      =  -4x

  9   +  4x=    4x+9    (Remember x, then y, then constant)

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becomes..(adding 4x to both sides, also adding 9 to both sides)...4x+5y=9

 

-11x     =    -20+9y

 11x+20=   +20 +11x  (x, then y, then constant)

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becomes...(adding 11x to both sides, also adding 20 to both sides)...11x+9y=20

 

Now we use elimation method:

4x+5y=9

11x+9y=20

 

to get x, we will make y in both equations equal....

 

9(4x+5y=9)

5(11x+9y=20)

 

We get....

36x+45y=81

55x+45y=100....subtraction can take place

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-19x      =-19....divide both sides by -19 to get x

 

-19x/-19. =-19/-19

 

x=1

 

Now substitute the value of x to get what y is....(x=1)

 

4(1)+5y=9

 

4+5y=9.....subtract 4 on both sides

-4    =-4

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5y=    5....divide both sides by 5 to get y

 

5y/5=5/5

 

y=1

 

Lets check.....x=1 and y=1

 

-9+5(1)=-4(1)

-4=-4....yes

-11(1)=-20+9(1)

-11=-11...yes

 

I hope this helped.

 

 

Answer 2

-9+5y=-4x

-11x=-20+9y

first equation becomes...

-9=-5y-4x

9=5y+4x

4x+5y=9

second equation becomes...

-11x=-20+9y

0=11x-20+9y

20=11x+9y

11x+9y=20 (2nd equation)

4x+5y=9 (1st equation)

multiply 2nd equation by 4 (all terms)

44x+36y=80

multiply 1st equation by 11 (all terms)

44x+55y=99

44x+36y=80 (2nd equation)

subtract the equations

        19y=19

            y=1

substitute y=1 into the first original equation...

-9+5(1)=-4x

-9+5=-4x

-4=-4x

x=1

(1,1) is the solution

Answer 3

-9 +5y = -4x

-11x = -20 + 9y

 

-9 + (9) + 5y + (4x) = -4x + (4x) + (9)

(-9y) -11x = -20 +9y + (-9y)

 

5y + 4x = 9     (multiply by -9/5)

9y + 11x = 20

 

-9y - 36/5x = -81/5

9y +11x  = 20

 

x (11-36/5) = (20 - 81/5)

 

x (19/5) =  (19/5)

 

x = 1

 

5y + 4(1) = 9

 

5y = 5

 

y = 1