Find an equation for the nth term of the sequence.

-4, -16, -64, -256, ...

Question

Find an equation for the nth term of the sequence.

-4, -16, -64, -256, ...

anonymous · Answer

an = a1 + (n – 1)d

usukidoll · Answer

I think we need to just find an equation that produces that string

usukidoll · Answer

-(4)^n and let n = 1,2,3,4...

zzr0ck3r · Answer

-(4)^1 = -4
-(4)^2 = -16
-(4)^3 = ?

usukidoll · Answer

lol ^ that's what I'm thinking too

anonymous · Answer

-64

usukidoll · Answer

think of it as this... ok there are - signs everywhere so we really need -... next I see a 4 16 64... hmmm square root of 16 is 4... 4^ 2 = 16.. cube root of 64 is 4...  4^3 = 64

anonymous · Answer

an = 4 • -4n

 an = 4 • -4n + 1

 an = -4 • 4n

 an = -4 • 4n - 1

usukidoll · Answer

so your equation would be -(4)^n

usukidoll · Answer

we don't need a_n

usukidoll · Answer

-(4)^n is the answer.. what if we let n  = 1 2 3 4? then we have -4,-16,-64,-256 which is what you want right?

anonymous · Answer

yes

usukidoll · Answer

^^ then that's the answer -(4)^n is your equation

anonymous · Answer

= -4 • 4n?

usukidoll · Answer

no ^

anonymous · Answer

4 • -4n

usukidoll · Answer

ignore JoyLin's suggestion... that's wrong

anonymous · Answer

because -4n is not one of my answer choices

anonymous · Answer

an = 4 • -4n

 an = 4 • -4n + 1

 an = -4 • 4n

 an = -4 • 4n - 1

anonymous · Answer

thats my choices

usukidoll · Answer

oh strange ... because you could just use what zzrocker and I said and that would be fine

anonymous · Answer

Thank you c: