If the coefficients of 2nd, 3rd and 4th terms in the expansion of `(1+x)^n` are in A.P. then find the value of `ndot`

Options

A. `2n^(2)+9n+7=0`
B. `2n^(2)-9n+7=0`
C. `2n^(2)-9n-7=0`
D. `2n+9n-7=0`

Answer

B