Question

If the coefficient of (2r+1)th term and (r+2 )th term arevequal in the expansion of (1+x)^43 then the value of r is

Answer 1

Please see the attachment

Answer 2

Value for r is 14

Step-by-step explanation:

$T_{r+1} = ^4^3{C_{r}}^{x^r}$

$T_{2r+1} = ^4^3{C_{2r}}^{x^2^r}$

$T_{r+2} = ^4^3{C_{r+1}}^{x^{r+1}}$

$^4^3C_{2r} = ^4^3C_{r+1}\ (As ^nC_r = ^nC_s)$

$or\ n = r+s$

$2r + (r+1) = 43$

$3r = 42$

r = 14