Question

I need help on this
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Answer 1

The first term
`a_(1)` = 4 and the formular for the nth term is :
`a_(n) = 4(-5)^(n-1)`

Here , we have a geometric sequence.

• nth term of a geometric sequence =
  `a_(n) = ar^(n-1)`
• a = first term ; r = common ratio

The common ratio , r is :

• r2/r1 = r3/r2

common ratio = -20/4 = -5

The first term,
`a_(1)` = 4

Now we have:

`a_(n) = 4(-5)^(n-1)`

Hence,
`a_(n) = 4(-5)^(n-1)`