Question

Solve the system by substitution. (Please Explain how you did it Ill give brainliest)

Answer 1

Because the last equation already has the y eliminated so just need to get the other two to eliminate the y too

multiply 4 to the first equation to eliminate y, and you get
-4x-4y-4z=-32
-4x+4y+5z=7
now get rid of y so all you have left is
-8x+z=-25 (let call this equation #4)

now take equation #3 and #4 together to solve for one of the variables, i’ll solve for z first so i’ll get rid of x by multiply the equation #4 all by 4, you get

8x+8z=16
-8x+z=-25
solve it and get 9z= -9; z=-1

now you have z so take it and ply it into equation #3
2x+2(-1)=4
2x=6; x=3

take both of them, plug it in equation #1
-3-y-(-1)=-8
-y=-6 ; y=6

done so the answer is (x,y,z) = (3,6,-1)

Answer 2

Answer:

  (x, y, z) = (3, 6, -1

Step-by-step explanation:

You can make a simple expression to substitute for x using the last equation.

  2x = 4 -2z

  x = 2 - z . . . . . . divide by 2

Now, substitute that into the first equation:

  -(2 -z) -y -z = -8 . . . .substitute for x

  -2 +z -y -z = -8 . . . . eliminate parentheses

 -2 -y = -8 . . . . . . . . . simplify

  6 = y . . . . . . . . . . . . add 8+y

We can substitute for both x and y in the second equation:

  -4(2 -z) +4(6) +5z = 7

  -8 +4z +24 +5z = 7 . . . . . eliminate parentheses

  9z = -9 . . . . . . . . . . . . . . .simplify, subtract 16

  z = -1 . . . . . . . . . . . . . . . . . divide by 9

And from our expression for x, we get ...

  x = 2 - z = 2 -(-1) . . . . . substitute for z

  x = 3

The solution is (x, y, z) = (3, 6, -1).