Question

PLEASEEEEE HELPPPPPP Find the sum of a finite geometric sequence from n = 1 to n = 6, using the expression –2(5)n – 1

Answer 1

My options are
1,223
–1,023
–7,812
7,812

Answer 2

@welshfella

Answer 3

@math1234

Answer 4

if its geometric the the nth term = a r^(n - 1)

here we have a - = -2 , and r = common ratio = 5 and n is the number of the term

so you need to plug thes values into the formula for n terms

Sn = a * (r^n - 1)
--------
r - 1

n will equal 6

Answer 5

* formula for the sum of n terms

Answer 6

as i said a = -2 , r = 5 and n = 6

Answer 7

so it's -2 times (5^6 - 1) over 5 -1?

Answer 8

yep

Answer 9

-7,812?

Answer 10

yep

Answer 11

Thank you so much!!!!!!!!!!!!!!!!!!!

Answer 12

yw