Question

Please help me and tell me how to do it

Answer 1

Answer:

1520

Step-by-step explanation:

Thiis is an arithmetic series. We can find "a", "d", and "l" from the series given.

1 + 4 + 7 +...+ 91 + 94

Here,

a is the first term (which is 1)

d is the common difference (the difference in a term and its previous term)

4 - 1 = 3

7 - 4 = 3

and so on...

d = 3

and

l is the last term (which is 94)

Now, from the series given, we can see that there are (32) terms. So

n = 32

Note: 94 - 1 = 93/3 = 31 + 1 = 32

Now, the formula to find the sum of n terms is:

$s_n=\frac{n}{2}(a+l)$

Substituting the values, we find the sum:

$s_n=\frac{n}{2}(a+l)\\s_{32}=\frac{32}{2}(1+94)\\s_{32}=16(95)\\s_{32}=1520$

The sum is 1520