Question

Find the sum of the series 3+7+11+,,,to 10th terms​

Answer 1

$\huge\bf\mathcal\red{Solution:-}$

$<i>$

A.P.=3,7,11...

a=3

d=4

n=10

Sn=?

Sn=n/2[a+(n-1)d]

=10/2[6+(10-1)4]

=5[42]

=5×42

$\huge\bf\boxed{=210}$

So,

the sum of the series upto 10 terms is 210

Answer 2

Answer:

Here,a1=3

d=4

n=10

Sn=n/2 [2a+(n-1)d]

S10=10/2 [2×3+(10-1)4]

S10=5 [6+36]

S10=5×42

S10=210

Therefore, the sum of 10 terms in the series is 210.

Step-by-step explanation: