Question

If n cr–1 = 56, ncr
= 28 and n cr+1 = 8, then r is equal to
(a) 8 (b) 6 (c) 5 (d) none of these

Answer 1

Answer:

b)6

you can do by opening the three eqs given by ncr formula and then divide any two eq by other by which u will get linear eqs in two variable in terms of n and r and then solve them

Answer 2

Answer:

correct answer is option b6