-6=8y=20 -10x-16y=4

Question

solve by elimantion x an y

Answer 1

-6x + 8y = 20     (multiply all the terms in this equation by 2)

-10x - 16y = 4     (keep this equation as is)

 

-12x + 16y = 40

-10x - 16y = 4

 

Now we add them which will cause the variable y to drop out.

 

-22x = 44

x = -2

 

Going back to the original equation -6x + 8y = 20, we put in our value for x in order to get a value for y.

 

-6(-2) + 8y = 20

12 + 8y = 20

8y = 8

y = 1

 

The solution is (-2, 1)

 

Answer 2

I think you wrote that first equation incorrectly.  I'm guessing the two equations are:

 

-6x-8y=20 and -10x-16y=4

 

If these are not correct, please edit your question to provide the correct equations.

 

Multiply the first equation by -2.  This will convert the -8y term to +16y that will add to the -16y in the other equation and eliminate the y-terms:

 

-2*[-6x-8y = 20]

12x +16y = -40

 

Now add this to the second equation:

 

 12x + 16y = -40

-10x -  16y =   4

----------------------

  2x  +  0   = -36

 

2x = -36

x= -18

 

Solve for y:

-6x - 8y = 20

-6*(-18) - 8y = 20

108 - 8y = 20

-8y = -88

y = 11

 

Check:

-6x - 8y = 20

-6*(-18) - 8*11 = 20

108 - 88 = 20

20 = 20                                CHECK!!

 

-10x - 16y = 4

-10*(-18) - 16*(11) = 4

180 - 176 = 4

4 = 4                                   CHECK!!