Question

find the sum of first 30 terms of an AP whose n-th term is given by 3+2n​

Answer 1

Answer:

$n = 30 \\ 3 + 2n = 3 + 2 \times 30 \\ = 3 + 60 \\ = 63$

l hope this answer is helpful for you ☺️

Answer 2

Aŋsweʀ :

• nth term of AP : 3 + 2n

We have to find sum of 30 terms of AP

putting n = 1

>> a = 3 + 2 × 1

>> a = 5

putting n = 2

>> a2 = 3 + 2 × 2

>> a2 = 3 + 4

>> a2 = 7

putting n = 3

>> a3 = 3 + 2 × 3

>> a3 = 3 + 6

>> a3 = 9

AP : 5 ,7 ,9 ....

• a = 5
• d = 7 - 5 = 2

$\sf \dashrightarrow \: s_{30}= \frac{n}{2} \big\{ 2 \times 5 + (30 - 1)2\big \} \\ \\ \sf \dashrightarrow \: s_{30}= \frac{30}{2} (10 + 29 \times 2) \\ \\ \sf \dashrightarrow \: s_{30}= 15(10 + 58) \\ \\ \sf \dashrightarrow \: s_{30}= 15 \times 68 \\ \\ \sf \dashrightarrow \: s_{30}= 1020$

Hence,

• sum of 30 terms of AP is 1020