Let a,b∈H∩K. Then a,b∈H and a,b∈K. Since (H,∗) and (K,∗) are subgroups of
(G,∗), a∗b∈H and a∗b∈K. By analogy for the inverse element a−1 of the element a in group G we have that a−1∈H and a−1∈K. Therefore, a∗b,a−1∈H∩K. So, we conclude that (H∩K,∗) is a subgroup of (G,∗).
Comments
Leave a comment