(a) Give an example of three planes in R^3 that have a common line of intersection. Justify your answer.

Question

(b) Give an example of three planes in R^3 that intersect in pairs but have no common point of intersection. Justify your answer.

(c) Give an example of three planes in R^3 that intersect in a single point. Justify your answer.

Answer 1

It should be easy to come up with (c)
In fact, most of your exercises will intersect at a point.

Now just adjust one of the planes so that it works for (a) and (b)
I'm sure your text has examples of such situations.

Answer 2

Here is an excellent video, with diagrams and example set of equations.
There are actually 3 videos, they should run into each other.

https://www.youtube.com/watch?v=duFRYId7kNU