Question

If Tn = 2n+3 , find Sn.??​

Answer 1

Answer:

If T

n

=2n+3 then,

T

1

=(2×1)+3=2+3=5

T

2

=(2×2)+3=4+3=7

T

3

=(2×3)+3=6+3=9

Therefore, S

3

is the sum of T

1

, T

2

and T

3

that is:

S

3

=T

1

+T

2

+T

3

=5+7+9=21

Hence, S

3

=21.

Answer 2

Given:-

$T_{n} = 2n + 3$

Solution:-

As we know that :-

$S_n =$ ∑$T_n$

therefore:-

⇒ $S_n =$ ∑$T_n$

⇒ $S_n =$ ∑$(2n + 3)$

⇒ $S_n = 2$∑n + 3∑1

⇒ $S_n = 2 * ( \frac{n (n+1)}{2} ) + 3n$

⇒ $S_n = n[n+1 + 3]$

⇒ $S_n = n(n+4)$

Thank you..........

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