Question

If the second, third and fourth terms in the expansion of (x + a)ⁿ are 240, 720 and 1080, respectively, then find the value of n.

Answer 1

It is given that 

T₂ = 240, T₃= 720 and T₄ = 1080

Now,

To eliminate x,

Putting r = 3 and 2 in above expression, we get