Question

If the sum of the n terms of an ap is Sn=3n2+5n then find it's common difference​

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Answer:

6

Step-by-step explanation:

$S_{1} = 3(1)^{2} + 5(1)$

$S_{1} = 3+5=8$

Now $S_{1} = a_{1}$ = 8

$S_{2} = 3(2)^{2} + 5(2)$

$S_{2}= 12 + 10 = 22$

$S_{2} = a_{1} +a_{2}$

$a_{2} = S_{2} - a_{1}$$a_{2}= 22 - 8 = 14$

$d = a_{2} -a_{1}$

$d=14-8\\Therefore, d=6$