Here's the question you clicked on:
Ambition
Write the sum using summation notation, assuming the suggested pattern continues. 8 - 40 + 200 - 1000 + ...
Sum (from n=1 to infinitive) (-1)^(n+1)* 8* 5^ (n-1)
that's what I got. hope this helps :)
\[S _{\infty}=\int\limits_{n=1}^{\infty}8\times (-5)^{n-1}\]