Three points are given: P = (2,1,0) , Q = (1,0,1) , R = (3,2,-1).

I'm supposed to find the plane that goes through P, Q, R in the form Ax + By + Cz = D.

My attempt:

M : (x,y,z) = P + t*PQ+ s*PR, s,t ∈R.= Q - P = (-1,-1,1) ,

PQPR= R - P = (1,1,-1).

This gives me a system of equaton where I use the elimination method to find out what the coefficients A, B, C and D are equal to, but I'm stuck at the second step:

x = 2 - t + s

y = 1 - t + s

z = + t - s

<=>

x = 2 - t + s

-x + y = - 1

x + z = 2

Did I do something wrong? / How do I proceed from here?