Выполни задание

Приведи к общему знаменателю:

а) \(\dfrac 1 2\) и \(\dfrac 1 3; \,\,\,\,\,\,\,\,\,\,\,\,\) б) \(\dfrac 1 5\) и \(\dfrac 1 6; \,\,\,\,\,\,\,\,\,\,\,\,\)

в) \(\dfrac 1 4\) и \(\dfrac 1 8; \,\,\,\,\,\,\,\,\,\,\,\,\) г) \(\dfrac 1 {14}\) и \(\dfrac 1 {21}\) .