x+2y=0

Question

x+3y+z=1
-4x-y-z=23

Answer 1

x + 2 y = 0 Subtract 2 y to both sides

x + 2 y - 2 y = 0 - 2 y

x = - 2 y

x + 2 y = 0

+

x + 3 y + z = 1

+

- 4 x - y - z = 23
___________________

- 2 x + 4 y = 24

- 2 * ( - 2 y ) + 4 y = 24

4 y + 4 y = - 24

8 y = 24 Divide both sides by 8

y = 24 / 8 = 3


x = - 2 y = - 2 * 3 = - 6

x + 3 y + z = 1

- 6 + 3 * 3 + z = 1

- 6 + 9 + z = 1

3 + z = 1 Subtract 3 to both sides

3 + z - 3 = 1 - 3

z = - 2

The solutions are:

x = - 6 , y = 3 , z = -2