Question

11. Find the sum of the arithmetic series. overset [22] underset{k=1}\huge{Sigma) (-4k - 13) =​

Answer 1

Answer:

okay, we need to add up for all k=1 till k=22

we could do it like this

(-4*1 -13) + (-4*2 -13) + (-4*3 -13) + ...

but this is long and boring, so we need another valid, yet vastly faster method to calculate this sum

we know that the "-13" part will occur 22 times, so let's write this component as "-13*22"

the -4k gents bigger with each step, k will take all the natural numbers from 1 to 22

so we could write

"-4 * (1+2+3+4+5+6+7...+21+22l

alot simpler and faster, but not fast enough

let's add up all numbers from 1 to 22 into one number

1 + 22 = 23

2 + 21 = 23

3 + 20 = 23

...

this works eleven times (bc we use up 2 numbers in each step), so the numbers from 1 to 22 added up are just

23*11= 230+23 = 252

now let's construct the final calculation

-4 * 252 -13*22 = -1294

there's your sum.

hope it helps you overall.

brainliest would be very kind ic some else leaves an answer, may it be just a greeting