Graphs Theory Hint about k-connected Show That G is a k-edge-connected graph if and only if there is no non-empty proper subset W to V (G), such that the number of edges joining W to V (G) - W is less k.
Can anyone help me or give me a hint? please
Lets prove it by the method of contradiction. 

Consider W such that the number of edges joining W to V (G) - W is greater than k. These are two disconnected components that are connected by greater than k number of edges in V (G), which contradicts the statement that the graph is k-connected.
Lets prove it by the method of contradiction. 

Consider W such that the number of edges joining W to V (G) - W is greater than k. These are two disconnected components that are connected by greater than k number of edges in V (G), which contradicts the statement that the graph is k-connected.