The given system consists of equations of planes. Notice that the coefficient of x in the first equation is the additive inverse of the coefficients of x in the second and the third equations; they will add to be 0. Let's use the Elimination Method to find a solution to this system.
x-y-2z=4 & (I) - x+2y+z=1 & (II) - x+y-3z=11 & (III)
We can start by adding the first equation to the second and the third equations to eliminate the x-terms.
The solution to the system is ( 0, 2, -3). This is the singular point at which all three planes intersect.
Now, we can check our solution by substituting the values into the system.