Question

Please help me with my algebra homework?

What is the sum of the geometric sequence 1,-6,36,.... if there are 7 terms?(1 point)

Answer 1

Explanation:

a=1

r=-6/1=-6

`S_(7)=a(1-r^n)/(1-r) =1(1-(-6)^7)/(1-(-6)) \\=(1+6^7)/(1+6) \\=(1+279936)/(7) \\=(279937)/(7) \\=39991`