Question

In an Arithmetic progression an =2n then the value of S3 is​

Answer 1

Answer:

12

Step-by-step explanation:

We know that aₙ is in the form of a + (n - 1) d

=> aₙ = a + (n-1) d

=> aₙ = (a - d) + nd

But here, given that, aₙ = 2n

Comparing these both d = 2, a-d = 0

=> a = d = 2

So,  First term is 2, difference = 2

Now,

$S_n = \frac{n}{2} [2a + (n-1)d] \\\\S_3 = \frac{3}{2} [2(2) + (3-1)2] \\\\S_3 = \frac{3}{2} [4 + 4] \\\\S_3 = 3 [2+2] \\\\S_3 = 3 \times 4\\\\S_3 = 12$

Hope it helps

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