What is the sum of the geometric sequence 1, −6, 36, … if there are 7 terms?

 The required sum is 39991.

Step-by-step explanation:  We are given to find the sum of the following 7-term geometric sequence:

1, -6, 36, . . ..

Here, the first term , a = 1

and

common ratio, 'r' is given by

We know that

the sum of first 'n' terms of a geometric sequence is given by

For the given geometric sequence, r = -6 < 1.

Therefore, the sum of first 7 terms will be

Thus, the required sum is 39991.

42

step-by-step explanation:

256/6=42