Find an equation for the plane through the points p=(0,0,0), q=(0,1,0), and r=(1,2,3)

Hello,

Assume Ax+By+Cz+D=0 the plane 's equation.

p=(0,0,0)==>A*0+B*0+C*0+D=0==>D=0

q=(0,1,0)==>A*0+B*1+C*0+0=0==>B=0

r=(1,2,3)==>A*1+0*2+C*3+0=0==>A=-3C
Let C=1==>A=-3

An equation of the plane is -3x+z=0

(1/x + 1)^2 + 6 (1/x + 1) +5