Write the formula for the geometric sequence.
5, 10, 20, 40, …

Question

Write the formula for the geometric sequence.
5, 10, 20, 40, …

anonymous · Answer

A.	an=40∙2n-1
	B.	an=40∙2n
	C.	an=5∙2n-1
	D.	an=5∙2n

***[isuru]*** · Answer

can u find the common ratio ?

anonymous · Answer

And for the first three. A. B. and C. the an is a^n but the n is on th bottom not the top. does that make scene?

anonymous · Answer

5(nx2)

where n is the place (1st number, 2nd number etc)

answer is D

***[isuru]*** · Answer

if we consider the 2 consecutive terms of a geometric progression a, b
the common ration (r) would be
           $$r = \frac{ b }{ a }$$

***[isuru]*** · Answer

Auxuris u r wrong

***[isuru]*** · Answer

and dont just give the answer

***[isuru]*** · Answer

the formula of a geometric progression is
         $$T_{n} = ar^{n-1}$$

anonymous · Answer

So @***[ISURU]***  umm.... ok sorry but im really bad at math. and im confused!

anonymous · Answer

Dont know why that just posted.

anonymous · Answer

so what do we have to figure out first.

anonymous · Answer

oh oops tried an example and figured that 

you'll have to subtract 1 because it starts with a 5

hang on, shouldn't it be 5x(n-1)2?

anonymous · Answer

wait what? @***[ISURU]***  @Auxuris you guys! I need help please? Anyone?