8x+y=-16 -3x+y=-5 solve by elimination

8x+y=-16

-3x+y=-5          Multiply the second equation by -1 and add it to the first equation

This gives

11x = =11        Divide both sides by 11

x = -1              

Now...just substitute this into either equation to find y......I'll use the first one

8(-1) + y = -16

-8 + y = -16       Add -8 to both sides

y = -8

Check both answers in the second equation

-3(-1) - 8 = -5

3 - 8 = -5

Yep...that works....!!!!

if your solving to combine the two equations into one you would write them on top of each other like this

8x+y=-16

-3x+y=5

then you would combine like terms straight down to get

5x+2y=-11

{x=-((11/3)), y=(40/3)}   or   {x=-3.6666666666666667, y=13.3333333333333333}

8x + y = -16    ...(1)

-3x + y = -5    ...(2)

Subtract 8x from both sides of (1) to get

y = -16 - 8x    ...(3)

Now eliminate y from (2) by replacing it with the right-hand side of (3)

-3x -16 -8x = -5

Collect the x terms

-11x -16 = -5

Add 16 to both sides

-11x = 11

Divide both sides by -11

x = -1 

Now eliminate x from (3) to find y

y = -16 -8*(-1)

y = -8

Check by putting the values for x and y back into (1)

8*(-1) + (-8) = -16  ok

and (2)

-3*(-1) + (-8) = -5  ok

Hi  Snip3s 

I just want to talk about your soln for a moment.

if your solving to combine the two equations into one you would write them on top of each other like this

8x+y=-16

-3x+y=-5    (you fogot the minus sign)

then you would combine like terms straight down to get

5x+2y=-11   NO THIS HAS NOT WORKED

You have started with the right idea but you line them up like this so that you can ELIMINATE one of the letters.

If you subtracted instead of adding you would have  8x--3x+y-y=-16--5 which becomes 11x=-11

x=-1   etc