Answer:
Your sum = [tex](-2)^{z}[/tex] - 1
S = ( (-2)^n - 1), If you let n = z, then S = (-2)^z - 1
Step-by-step explanation:
I can use a formula to find the sum of the first n terms.
we have -3, 6, -12, 24, ... etc.
common ratio = r = -2
first term = -3
a_1 = -3
Then: a_n = a_1 * r ^(n -1)
a_n = (-3) * (-2)^(n - 1) is the general formula for the nth term
Sum of first n terms = S = a_1 * (r^n - 1) / (r - 1)
so...
S = (-3) * ((-2)^n - 1 )/ (-2 - 1)
which simplifies to
S = (-3) *((-2)^n - 1) / (-3)
S = ( (-2)^n - 1)
If you let n = z, then S = (-2)^z - 1
