Mark the correct alternative in the following : If the coefficients of the term and the term in the expansion of are equal, then the value of n is

Question

Philoid · Accepted Answer

Given:

For nth term ; k=n-1

So for (n+1)th term ; k= n

& for (n+3)th term ; k =n+2

Coefficients for the above terms are equal;

(20-n)(19-n) = (n+2)(n+1)

380-39n+n² = n²+3n+2

42n-378=0

n=9