Find the equation of the plane through (1,2,-1) parallel to the plane 5x+y+7z=20.

Question

dumbcow · Answer

wait sorry i think i over complicated it,
if its parallel then it will have the same normal

-->5x+y+7z = C
plug in given point to find C

anonymous · Answer

So, c=0,
so the equation would be 
--> 5x+y+7z=0?

dumbcow · Answer

yes

anonymous · Answer

Thanks :)
So, all you have to do with these questions is plug in the points?

dumbcow · Answer

if the planes are parallel, then yes

anonymous · Answer

How about perpendicular?

dumbcow · Answer

then you have to find a vector that is perpendicular to the normal by setting dot product =0

--> 5a+b+7c = 0
choose a,b,c such that it satisfies equation

then new plane is ax+by+cz = C
then plug in point

anonymous · Answer

Oh Ok.

anonymous · Answer

Thanks :)