Question

Find a, b and n in the expansion of (a + b)^n if the first three terms of the expansion are 729, 7290 and 30375, respectively.

Answer 1

It is known that (r + 1)^th term, (T _r +1), in the binomial expansion of (a + b) ⁿ is given by .

The first three terms of the expansion are given as 729, 7290, and 30375 respectively.

So, we obtain

Dividing equation 2 by 1 we get