Geometric means you multiply to get the next number. The first one is geometric with r =3/4 The second one is with r= 1/4. The third one is with r=3.5 The fourth is NOT. The fifth one is with r=1.1 The sixth is NOT
First you multiply the last term by the first term (3h+16h+15). Then find numbers that add to 16 and multiply to 15 then add or subtract it from (3h+15)(3h+1). Then factor if possible (h+5)(3h+1)