Find an explicit rule for the nth term of the sequence.

7, -7, 7, -7, ...

Question

Find an explicit rule for the nth term of the sequence.

7, -7, 7, -7, ...

anonymous · Answer

@Nnesha 
Would it be  an = 7 • (-1)n - 1?

anonymous · Answer

Or  an = 7 • (-1)n

xapproachesinfinity · Answer

depends what you start with n=0 or n=1?

anonymous · Answer

How can I tell? @xapproachesinfinity

xapproachesinfinity · Answer

if you decided to start with n=1 as your first term
then a_n= 7.(-1)^{n-1}

welshfella · Answer

your first one is correct

7 * (-1)^(n-1)

anonymous · Answer

Oh ok thanks so much! Could you help me with another one?

xapproachesinfinity · Answer

there is no consequence in choosing an=7(-1)^n as a correct answer as well

xapproachesinfinity · Answer

it really depends on what i said

anonymous · Answer

For 
Find the vertices and foci of the hyperbola with equation quantity x minus 5 squared divided by 144 minus the quantity of y minus 4 squared divided by 81 = 1.

Would the answer be -5?

welshfella · Answer

this is a geometric series with common ratio = -1

xapproachesinfinity · Answer

both are good as i see it

xapproachesinfinity · Answer

just point that n>0 if you choose the first

xapproachesinfinity · Answer

otherwise choose the second

anonymous · Answer

Ok thanks
For 
Find the vertices and foci of the hyperbola with equation quantity x minus 5 squared divided by 144 minus the quantity of y minus 4 squared divided by 81 = 1.

Would the answer be -5?

xapproachesinfinity · Answer

post that on different post

anonymous · Answer

Ok

welshfella · Answer

I see your point  "xapproachesinfinity but in the case of  a geometric series  it always seems to  start with n = 1.