Question

if 5+9+13+.......upto n terms divided by 7+9+11+....upto 12 terms =5/12,then n is equal to

Answer 1

Heya

∆First is an A.P. with c.d. 4, first term = 5

Hence, sum of n terms :
$n(2n + 3)$
Now, second A.P. is the sum of odd numbers

Hence, the sum of first 12 terms after 5 is
${(15)}^{2} - (1 + 3 + 5)$
$= 216$
Finally,

$\frac{n(2n + 3)}{216} = \frac{5}{12}$
$= > 2 {n}^{2} + 3n - 90 = 0$
$= > (n - 6)(2n + 15) = 0$
Hence, from here we get :

$n = 6$

Answer 2

hi write answer is here

n=6