Let R be a non-emply relation on a collection of sets defined by $${A^R}\,B $$ if and only if $$A\, \cap \,B\, = \,\phi $$. Then, (pick the true statement)

Let R denote the set of real numbers. Let f: $$R\,x\,R \to \,R\,x\,R\,$$ be a bijective function defined by f (x, y ) = (x + y, x - y). The inverse function of f is given by

Let A be the set of all nonsingular matrices over real numbers and let * be the matrix multiplication operator. Then

Some group (G, o) is known to be abelian. Then, which one of the following is true for G?