Question

What is the sum of the arithmetic sequence 8, 15, 22 …, if there are 26 terms?

Answer 1

First term is 8 here..

Common difference is 15 - 8 = 7


Use:

\[\large Sum = \frac{n}{2}(2a + (n-1)d)\]

a = 8 d= 7 and n= 26

can you do it??

Answer 2

Trying or not @RoLexx

Answer 3

i dont get it

Answer 4

Where you do not get it??

Answer 5

You have all the values just plug in the formula..

Answer 6

or you think this is the formula:

\[\large Sum = \frac{n(first \quad + \quad last)}{2}\]

Answer 7

Both the formulas are same..

Answer 8

Can you plug in the values in the very first formula:

a = 8 d = 7 and n = 26

Find the Sum..

Answer 9

See:

\[\large Sum = \frac{26}{2}(2(8) + (26-1)(7))\]

\[Sum = 13(16 + 25 \cdot 7) \implies 13(16 + 175)\]

Answer 10

Use calculator and fine the value of : \(13 \times 191\) = ??

Answer 11

2483

Answer 12

Absolutely..
Well Done..

Answer 13

Thanks

Answer 14

Welcome dear..