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
X intercept: y = 0
y= -3/4x -4
0 = -3/4 x - 4
4= -3/4 x
4 • -4/3 = x
-5.3 = x
y intercept: x = 0
y = -3/4 x -4
y = -3/4 (0) -4
y = -4
the points are (-5.3, 0) and (0, -4)