Question

What is the sum of the first 10 terms of this geometric sequence? 3, –6, 12, –24, …

Answer 1

Explanation:

a1=3

r=-6/3=-2

`S_(10)=a1(1-r^n)/(1-r)\\ =3(1-(-2)^(10))/(1-(-2)) \\=3(1-1024)/(3) \\=3(-1023)/(3) \\=-1023`

Answer 2

(-1023)

Explanation:

3+(-6)+12+(-24)+48+(-96)+192+(-384)+768+(-1536)