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

Answer 1

just plug in the values for n.
a1 = 21 - 2*1^2 = 21-2 = 19
a2 = 21 - 2*2^2 = 21-8 = 13
and so on

Answer 2

it’s option D

Answer 3

1. D 19,13,3,-11,-29
2. B -1,4,9,14,19
3. A an=5/2n-11/2;37
4. D an=an-1+2;a1=8
5. C 306
6. B -105/2
7. C 36
8. C -675
9. A (-28+3n)
10. D 114