Question

Solve the following system of equations.

2x – 3y + z = –1
3x + 2y + 2z = –1
x – y – 3z = –4

(–1, 0, 1)

(1, 1, 4)

(–1, –1, –2)

(1, 2, 1)

Answer 1

Multiply the first by -2 and add to the second to get
\[-4 x + 6 y - 2z = 2\\
3x + 2y + 2z = –1

-x + 8y =1

\]
Only the first (-1,0,1) satisfies -x+8 y=1

Answer 2

\[
-4 x + 6 y - 2z = 2\\
3x + 2y + 2z = –1\\

-x + 8y =1
\]

Answer 3

You only can use this method if the question is that one of the choices is the solution. In this case, it is.