Question

Determine Sn for the geometric series? f(1)=2, r=-2, n=12

Answer 1

`S_(12)=8190/11`

Explanation:

`"the sum to n terms of a geometric sequence is"`

`•color(white)(x)S_n=(a(r^n-1))/(r-1)`

`"where a is the first term and r the common ratio"`

`"here "a=2,r=-2" and "n=12`

`S_(12)=(2((-2)^(12)-1))/(12-1)`

`color(white)(xxxxxx)=(2(4096-1))/11=8190/11`