On energy of line graphs

The energy E(G)E(G) of a simple graph G is the sum of absolute values of the eigenvalues of its adjacency matrix. The line graph of G   is denoted by LGLG. We obtain a relation between E(LG)E(LG) and E(G)E(G), and establish bounds on E(LG)E(LG). Moreover, we present results pertaining to equienergetic and hyperenergetic graphs.