Respuesta :

MathPhys

Answer:

Your answer is correct.  The series is a geometric series with common ratio -1/4 and first term 40.  So each term is:

an = 40 (-1/4)^(n−1)

So the sum of the first 10 terms is:

∑(n=1 to 10) [ 40 (-1/4)^(n−1) ]