Question

explain why we know 3,2,2,2,1 is not the degree sequence of a tree

Answer 1

ANSWER :-

Given that, 3,2,2,2,1 is not a degree sequence of a tree.

Here,we need to explain why 3,2,2,2,1 is not a degree sequence of a tree.

given 5 vertices .

and edges also equal to 5

The sum of given degrees is ( 3+2+2+2+1) = 10.

Since this sum equals twice the number of edges in a graph.

But here the graph is not possible with five edges.

A tree must have 4 edges.but we have 5 edges.

Thus , 3,2,2,2,1 is not the degree sequence of a tree.

hence proved.