Answer:
-39991'
Explanation:
We require the sum of 7 terms of the G.S. -1, 6, -36 .....
The common ratio r = 6/-1 = -6 and the first term = -1.
Sum of n terms = a1 . (r^n - 1) / (r - 1)
Sum of 7 terms = -1 * (-6)^7 - 1) / (-6 - 1)
= -1 * 39991
= -39991 (answer).