Question

@hartnn
Write the sum using summation notation, assuming the suggested pattern continues.

5 - 15 + 45 - 135 + ...

Answer 1

do you see any pattern in that??

like if you multiply/divide current term with a certain number,
you get the next term??

Answer 2

the cerrent term multiplied by 3

Answer 3

if you multiply it by just a 3, then you will get all positive numbers,
try multiplying by -3!

Answer 4

so \[\sum_{n=0}^{\infty}5(-3)^n\]

Answer 5

?

Answer 6

so,
using a summation notation in general,
\(\Large \sum \limits_{n=0}^{n=\infty } f(n)\)

oh you already got it!

Answer 7

ok thanks!

Answer 8

yes thats correct :)