Question

Answer both correctly, please and I will mark brainliest for correct answers.
Find the sum of each arithmetic series series with 12 terms, =sub 1 = 3 and sub=sub 12 ,= 25

Answer 1

Answer:

168 qnd 161

Step-by-step explanation:

For the first question,

The number of terms (n) is 12. The first term (a) is 3 and the last term (l) is 25

The formula for finding the sum of an arithmetic series when the last term is given is:

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

Putting the given values in the formula, we get

S = 12/2 × (3+25)

= 6 × 28

= 168

For the second question, the number of terms is 7. The first term is 5 and the last term is 41.

Using the same formula, we get the sum as:

S = 7/2 × (5+41)

= 7/2 × 46

= 7×23

= 161