### Video Transcript

Using the Venn diagram, find not π union π.

Itβs worth noting that other notation can be used for this kind of question, like this. So we got π union π inside of the parentheses. And weβve got a prime, which also denotes that it means not π union π. But what does not π union π mean. Well, we can think about it as not π or π, and thatβs because union means or.

So how would this look on a Venn diagram? Well, if I was to draw a sketch of a Venn diagram, which we have here. Weβve got π and π. Well, if we would say everything in π, it would look like this. But we want π or π. So what Iβve done now is shade in π. So that means π or π would be anything in π or anything in π. Itβs not and so it doesnβt have to be both. It means anything there at all.

So therefore, if weβre looking for not π or π or not π union π, then therefore, itβs gonna be anything that is not shaded in pink. So what Iβve done is Iβve shaded in blue. So itβs all the area around the outside. So therefore, in our question, all the area around the outside contains the three numbers three, seven, and nine. So therefore, we can say that the set of numbers that satisfy not π union π are going to be nine, three, and seven.