Question

find the sum of first 16 terms of ap 2,7,12​

Answer 1

Answer:

n=16

a=2

d=7-2=5

$Sn = \frac{n}{2}({2a + 15d})\\ = 8 \times (4 + 75) \\ = 8\times 79 \\ = 572$

Answer 2

Answer:

Given an AP is:-

2 , 7 , 12 . . . . . . . . . . .

IN THIS ARTHEMATIC PROGRESSION

First term = a = 2

And

Common difference = d = 5

As we have to calculate sum of 1st 16 terms s

So,

we will take

Total no. of terms = n = 16

NOW,

We know that sum of first n terms of an AP is given by the formula

$\large \boxed{\boxed{S_n = \frac{n}{2}(2a + (n - 1)d) }}$

So

Here

$\large S_{16} = \frac{16}{2} (2 \times 2 + 15 \times 5) \\ \\ = 8 \times 79 \\ \\ = 632$

which is the required sum