The given sequence is an infinite geometric sequence with a common ratio of -2. The first term of the sequence is -50, and each subsequent term is obtained by multiplying the previous term by -2.
The formula for the sum of an infinite geometric series with first term a and common ratio r is:
S = a / (1 - r)
Plugging in the values for a and r, we have:
S = -50 / (1 - (-2)) = -50 / (1 + 2) = -50 / 3
Therefore, the sum of the infinite geometric sequence -50, -25, -12.5, ... is -50 / 3.