no. of edges

Question

A graph G has k isolated vertices and n + k vertices. The maximum number of edges graph G can have?

a) n(n-1) b)n(n-1)/2) c) n(n-k+1)/2 d) n(n+k-1)/2

Comments

It should be ⁿC₂ 

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is n+k  is total number of vertices?

the first statement seems ambigious

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For maximum number of edges . Divide graph into k component such a way that (k-1) components having 1 vertex and last component had remaining vertices .

Last component will get (n+k-(k-1)) vertices i.e ; (n+1) verices .

Maximum numbers of edges = (n+1)*(n)/2

There is no option

Answer 1

Total number of vertices n+k

Number of isolated vertex k

Total components k+1,

Maximum number of edges  0*K (For k isolated vertex) n(n-1)/2 for reaming 1 component

Total Maximum Edges $\frac{(n*(n-1))}{2}$

Option B