Question

Solve the following system of equations for all three variables.

-9x-y+2z= -4
-6x+y+5z= 2
-4x+y+5z= 6

Answer 1

x=2, z=4, y=-6

Explanation:

Add

-9x-y+2z= -4

-6x+y+5z= 2

-9x-6x is -15x

-y+y is 0

2z+5z is 7z

-4+2 is -2

So the equation now looks like this: -15x+7z=-2

Subtract

-6x+y+5z= 2

-4x+y+5z= 6

So the equation will look like this:

-6x+y+5z= 2

-(-4x+y+5z= 6)

-6x+4x is -2x

y-y is 0

5z-5z is 0

2-6 is -4

So the equation now looks like this: -2x=-4

You can find x by dividing -2 on both sides:

x=2

So 2 is x

Now you can substitute x into 2

-15(2)+7z=-2

-30+7z=-2

7z=28

Divide 7 on both sides:

z=4

So now you can substitute z into 4 (For any of the three equation)

-4(2)+y+5(4)=6

-8+y+20=6

20 minus 8 is 12

y+12=6

Subtract 12 on both sides:

y=-6

So the answers are

x=2, z=4, y=-6

Hope this helps!