Question 227981
equation of plane: ax+by+cz=d ----> <a,b,c> is normal vector 


Plug in normal vector u=i-2j+4k: ax+by+cz=d ---> x-2y+4z=d


Plug in point (x,y,z)=(2,3,4) ----> 2-2(3)+4(4)=12=d


equation of plane is x-2y+4z=12