Question

PLEASE HELP!!
MEDAL WILL BE GIVEN. ALSO FAN :)

Answer 1

\[\sum_{3}^{5} (k^2 - 10)\]

Answer 2

Find the sum of the sequence.

Answer 3

@jim_thompson5910
@mathslover
@mathsmind
@satellite73
@wio
@AravindG
@dumbcow

Answer 4

well u can use the formula for solving this, note u may split ur summation into sum of k^2 and sum of -10

Answer 5

ok i did that

Answer 6

i will finish the calculus guy and come and solve ur problem

Answer 7

please do as soon as u can?
anyone else can help me right now??

Answer 8

@jim_thompson5910 @mathslover @mathsmind @satellite73 @wio @AravindG @dumbcow

Answer 9

\[\sum_{2}^{5}k^2-\sum_{2}^{5}10\]

Answer 10

okaii got you, whats next

Answer 11

@mathslover
@mathsmind

Answer 12

???

Answer 13

wait i am replying to 002830948028498298409238 msgs hehehehe

Answer 14

and i am coding with php be patient please

Answer 15

ok

Answer 16

PLEASE SOMEONE HELP ME :(

Answer 17

@ghazi

Answer 18

@jim_thompson5910

Answer 19

@karatechopper

Answer 20

ill help u if u help meh

Answer 21

\[=\frac{1}{6}k(k+1)(2k+1)\]

Answer 22

how did u get that?

Answer 23

this is the formula for summing K^2

Answer 24

u can prove that using induction

Answer 25

and the sum of 10 would be 10k

Answer 26

now there is a trick in ur question

Answer 27

yeah?

Answer 28

k should start from 1, so u need to shift ur sum by 2 units do u get that?

Answer 29

so the whole summation must be shifted this is the only trick of ur question

Answer 30

so how do i do that?

Answer 31

the way i do it!

Answer 32

how?

Answer 33

@dumbcow please help?

Answer 34

@mathsmind

Answer 35

when k = 3

k^2 - 10 =3^2 - 10 = 9 - 10 = -1

so when k = 3, the term is -1

Answer 36

when k = 4

k^2 - 10 =4^2 - 10 = 16 - 10 = 6

when k = 4, the term is 6

Answer 37

when k = 5

k^2 - 10 =5^2 - 10 = 25 - 10 = 15

so when k = 5, the term is 15

Answer 38

add up the terms: -1 + 6 + 15 = 20

Answer 39

therefore,

\[\Large \sum_{3}^{5} (k^2 - 10) = 20\]

Answer 40

why did u stop when k = 5

Answer 41

the answer is 20

Answer 42

because the question asks u to stop at 5

Answer 43

\[\Large \sum_{3}^{5} (k^2 - 10)\] means you add the terms for k = 3, k = 4 and k = 5 and that's it