Examine whether the following sequences are in H.P. :
`{(1)/(7), (1)/(9), (1)/(12), (1)/(16),…}`

Examine whether the following sequences are in H.P. : {(5)/(4), (10)/(13), (10)/(18), (10)/(23),…}

Examine whether the following sequences are in H.P. : {(1)/(a-3b), (1)/(a-2b), (1)/(a-b), (1)/(a),…}

Examine whether the following sequences are in H.P. : {(3)/(2), (3)/(11), (3)/(17), (3)/(23),…}

Check whether the following sequences are in A.P. (1)/(2), (1)/(3), (1)/(4), (1)/(5), …

Examine whether the following sequences are in H.P. : {(1)/(c + 3d'), (1)/(c + 2d'), (1)/(c'), (1)/(c - 3d'),…}

Which of following sequences are in G.P. (1)/(3), (1)/(6), (1)/(12), …,

Check whether the following sequences are in A.P. (-1)/(3), 0, (1)/(3), (2)/(3), …