The number of integral terms in the expansion of (31/2+51/4)680 is equal to ___________ . [2023]
(171)
The expansion of the general term is
=Cr680(31/2)680-r(51/4)r=Cr6803680-r25r4
Possible values of r, where r4 is an integer
r=0,4,8,12,…,680
All these values of r are accepted as well.
Hence, number of integral terms=171