Step by step
The question
Question: find the plane through (0, 3, −2) with normal vector n = ⟨5, −2, 1⟩.
1 Draw it
A normal vector is an arrow at a square corner to the plane.
The plane goes through the point,
and the normal sticks straight out of it.
2 Write the plane
The rule: a(x − x₀) + b(y − y₀) + c(z − z₀) = 0.
The normal gives a, b, c.
The point gives x₀, y₀, z₀.
Careful!
The normal's numbers go in front.
The point's numbers go inside the brackets, with a minus.
3 Open the brackets
What is in front of a bracket multiplies every part inside.
A minus in front changes the signs inside.
Add the plain numbers: they make 8.
Move the number to the right: take away 8 on both sides.
So the plane is 5x − 2y + z = −8.
4 Check
Let's check: put the point (0, 3, −2) in.
We get −8.
Right!
Let's look back.
First: draw it.
Then: write the plane.
Then: open the brackets.
Last: check.