Question

Write the first five terms of the sequence defined by the explicit formula an=21-2n^2

A. 21, 19, 13, 3, -11

B. 20, 17, 12, 5, -4

C. 23, 29, 39, 53, 71

D. 19, 13, 3, -11, -29

Answer 1

the answer to the squence is either d or a i believe

Answer 2

Answer: D. 19, 13, 3, -11, -29

Explanation:

The first five terms can be found by taking n= 1,2,3,4,5

The given sequence is :

`a_(n) =21-2n^(2)`

Substituting n = 1,2,3,4,5 we have :

`a_(1) =21-2(1^(2) )=21-2=19.`

`a_(2) =21-2(2^(2) )=21-8=13`

`a_(3) =21-2(3^(2) )=21-18=3`

`a_(4) =21-2(4^(2) )=21-32=-11`

`a_(5) =21-2(5^(2) )=21-50=-29`

The first five terms of the sequence are

D. 19, 13, 3, -11, -29