Equation 1) 3x + 2y - 5z = 3
Equation 2) 4x - 2y - 3z = -10
Equation 3) 5x - 2y - 2z = -11
Add equation 1 with equation 2.
Equation 4) 7x - 8z = 7
Then subtract equation 3 from equation 2.
Equation 5) -x -z = 1
Multiply all of equation 5 with 7.
5) -7x - 7z = 7
4) 7x - 8z = 7
Add equations together.
z = 14
Plug in 14 for z in equation 4.
7x - 8z = 7
7x - 8(14) = 7
7x - 112 = 7
7x = 119
x = 17
Plug in 17 for x in equation 1, and 14 for z.
1) 3x + 2y - 5z = 3
3(17) + 2y - 5(14) = 3
51 + 2y - 70 = 3
2y - 19 = 3
2y = 22
y = 11
So, x = 17, y = 11, and z = 14
~Hope I helped!~
