Question

Evaluate the series

Answer 1

\[\sum_{n=3}^{8} 5n\]

Answer 2

@ParthKohli

Answer 3

@apoorvk

Answer 4

add 'em from n=3 till n=8

so basically ---> 5x3 + 5x4 + 5x5 +....+5x8

Answer 5

'x' ==> multiplication sign and not the 'eks' :P

Answer 6

15 + 20 + 25 + 40 = 100

Answer 7

r = 5
a1 = 15
an = 40
n = 5 [8-3]
Sn = a1 (1-r^n/1-r) = 15 * (1 - 5^5/1-5) = 15 * 6 = 90

Answer 8

125, 38, 210, or 165 is the final answer

Answer 9

@ParthKohli @apoorvk @Callisto helpp!

Answer 10

It's either one of these answers but don't just give me the answer, explain how u got it! :D

A)125
B) 38
C) 210
D) 165

Answer 11

\[\sum_{n=3}^{8}5n\]\[ = 5(3) + 5(4) + 5(5) + 5(6) + 5(7) + 5(8)\]\[=5( 3+4+5+6+7+8)\]\[=5(33) =? \]

Answer 12

Using the rules of summation,
\[5(8*(8+1)/2) - 5(2(2+1)/2) = 165\]

Answer 13

165! tnx callastino and adj!

Answer 14

callisto....
Welcome

Answer 15

You Welcome :)