Give an exanple of a group g in whieh ofa ofb ofab 2veriy whether d a subgroup of d let4 be the subgroup of rotatik n d fud the eentralizer of a i d 4let g e be

Give an exanple of a group G in whieh ofa ofb ofab 2Veriy whether D a subgroup of D Let4 be the subgroup of rotatik n D Fud the eentralizer of A i D 4Let G e be a group. and let a, be G. Show that the set H tha a G is a subgroup of G. Find all generators of Z 6. Verify whether all non-trivial proper subgroups of (R, +) are cyclic.