Given the equation: $3x + y - z = 6$.

1. Draw a graph.

   Hint (a):

   Notice that there are three variables. Find the three intercepts.

   Answer (a):

   

2. Is $(1, 2, -1)$ on the graph? Justify your answer.

   Hint (b):

   Does the point make the equation true?

   Answer (b):

   Yes, it is a solution to the equation.