Question

For G.P
a=2,r=-2/3 ,find S6

Answer 1

Answer:

5.47

Step-by-step explanation:

S = a ( 1 - r^n )/(1- r)

n=6

Answer 2

Answer:

1.095 ( approx )

Step-by-step explanation:

∵ Sum of a GP is,

$S_n=\frac{a(r^n-1)}{r-1}$ ( when r > 1 )

$S_n=\frac{a(1-r^n)}{1-r}$ ( when 0 < r < 1 )

Where,

a = first term,

r = common ratio,

n = number of terms,

Here, a = 2, r = $-\frac{2}{3}$ n = 6,

$\implies S_6=\frac{2(1-(-\frac{2}{3})^6)}{1+\frac{2}{3}}$

$=1.09465020576$

$\approx 1.095$