Question

Write the explicit formula for the geometric sequence.

a1 = -5 a2 = 20 a3 = -80
A. an = -5 • (-4)n

B. an = -5(-4)n-1

C. an = -4(-5)n-1

D. an = -5 • (4)n

Answer 1

@GraceJaylene
@deezgurls

I got D.

Answer 2

Write the recursive formula for the geometric sequence.

a1 = -2 a2 = 8 a3 = -32
A. an = -4 + an-1

B. an = -2 + an-1

C. an = -2 • an-1

D. an = -4 • an-1

And C here

Answer 3

@Peter14

Answer 4

@Frostbite HELP! plz :)

Answer 5

@GraceJaylene !!!!! DDDD:

Answer 6

a1 does not equall; -5*4(1)

Answer 7

yeah could u explain this to me? :)

Answer 8

since its geometric, we want to determine a common "r" such that

a1 = -5 * r = 20
a2 = 20 * r = -80
a3 = -80

r = 4 is good

and your options appear to be missing the ^ to indicate an exponent

Answer 9

in any case

an = a1 * r^(n-1) is the explicit formula for a geometric seq

Answer 10

err, -4 is fine for r

Answer 11

the recurrsive mirrors the setup that gets you to find "r"

a1 = k * r = a2 * r = a3 *r = .....= an-1 * r = an * r = an+1*r = .....

Answer 12

ohh

Answer 13

a1 = -2 * r = 8
a2 = 8 * r = -32
a3 = -32 + r = ....

an = r * an-1

Answer 14

i see it :P

Answer 15

good luck ;)

Answer 16

thanks :P