SOLUTION: Show that vector n [2, 4, 6] is perpendicular to every vector on the plane: 2x + 4y + 6z = 12 I'd offer what I've tried, but honestly, I have no clue. My textbook doesn't seem

Algebra ->  College  -> Linear Algebra -> SOLUTION: Show that vector n [2, 4, 6] is perpendicular to every vector on the plane: 2x + 4y + 6z = 12 I'd offer what I've tried, but honestly, I have no clue. My textbook doesn't seem       Log On


   



Question 941323: Show that vector n [2, 4, 6] is perpendicular to every vector on the plane:
2x + 4y + 6z = 12
I'd offer what I've tried, but honestly, I have no clue. My textbook doesn't seem to illustrate a similar problem, and I cannot find a similar solution in my notes.
Please assist! It's greatly appreciated!

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let u and v be two vectors in the plane.
u=(x%5B1%5D,y%5B1%5D,z%5B1%5D)
v=(x%5B2%5D,y%5B2%5D,z%5B2%5D)
Since they're in the plane,
1.2x%5B1%5D%2B4y%5B1%5D%2B6z%5B1%5D=12
2.2x%5B2%5D%2B4y%5B2%5D%2B6z%5B2%5D=12
If you subtract eq. 1 from eq. 2,
3.2%28x%5B2%5D-x%5B1%5D%29%2B4%28y%5B2%5D-y%5B1%5D%29%2B6%28z%5B2%5D-z%5B1%5D%29=0
.
.
.
If they are perpendicular to the normal vector, then the dot product of each vector with the normal will be zero.
u%2An=0
(x%5B1%5D,y%5B1%5D,z%5B1%5D)*(2,4,6)=0
4.2x%5B1%5D%2B4y%5B1%5D%2B6z%5B1%5D=0
.
.
v%2An=0
(x%5B2%5D,y%5B2%5D,z%5B2%5D)*(2,4,6)=0
5.2x%5B2%5D%2B4y%5B2%5D%2B6z%5B2%5D=0
So then if I subtract the two dot products,
6.2%28x%5B2%5D-x%5B1%5D%29%2B4%28y%5B2%5D-y%5B1%5D%29%2B6%28z%5B2%5D-z%5B1%5D%29=0
Comparing eq. 6 to eq. 3, you recognize they are identical.