Question

Math Questions!!

Answer 1

you know the formula for n'th term of geometric sequence ?

Answer 2

Yes

Answer 3

let the first term be 64 then, and +7 to find 14, and -6 to find 1

Answer 4

r = common ratio = -2 is given

if you plug in n =7, you'll get expression for a7
and you already know a7 = 64

Answer 5

-2 assuming typos

Answer 6

a1 is unknown

\(\large a_n = a_1 r^{n-1} \\ \large 64 = a_1 (-2)^{7-1}\)

Answer 7

\[b_1=64(-2)^{1-1}\]
\[b_m=64(-2)^{m-1}\]

Answer 8

Two different numbers.. :I

Answer 9

when for m=n+6, n=m-6

Answer 10

which 2 different numbers ?

Answer 11

2 different approaches is all :) same structure

Answer 12

You wrote al is unknown but amistree wrote n is unknown...

Answer 13

follow either one of us....if you see all comments, you will get confused...

Answer 14

where a sequence starts is immaterial, as the distances between terms does not change

Answer 15

with both the approaches, you will get the same answer

Answer 16

I see, thank you.

Answer 17

I have one more question. Do you mind? :I

Answer 18

ask

Answer 19

(64)
a = 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14
b = -5,-4,-3,-2,-1, 0, 1, 2, 3, 4, 5, 6, 7, 8

Answer 20

negative value of 'n' is not so conventional...

Answer 21

letting the starting point be 0 i find more useful:

a1 = b(-6)
a(14) = b7

bn = 64(-2)^n

Answer 22

also , -4,12, 36..
is not a geometric sequence at all
check the question ? is it -36 ?

Answer 23

Oh yes. :I Sorry

Answer 24

find the common ratio 'r' first

if |r|<1 , then use the sum formula
\(\Large S_n = a_1 \dfrac{r^n-1}{r-1}\)

a1 = 1st term = -4

if |r| > 1, then the series diverges and there will be no sum

Answer 25

r = -3
a1 = -4
n =7
plug these in

Answer 26

\(S_7 = (-4) \dfrac{(-3)^7-1}{(-3-1)}\)

calculate that ^

Answer 27

-2188?

Answer 28

thats correct :)