Question

2x + 3y – z = 1
3x + y + 2z = 12
x + 2y – 3z = –5

Answer

(3, 1, –2)

(3, 1, 2)

(–3, 1, 2)

(3, –1, 2)

Answer 1

last one
http://www.wolframalpha.com/input/?i=2x+%2B+3y+%E2%80%93+z+%3D+1+%2C3x+%2B+y+%2B+2z+%3D+12%2C+x+%2B+2y+%E2%80%93+3z+%3D+%E2%80%935

Answer 2

Answer is (3,-1,2). You could, for example, use equation (3) to eliminate the x variables from equations (2) and (3). Then solve that 2x2 system for y and z.