Question

Can she get some help

Answer 1

Answer:

Step-by-step explanation:

the formula for an arithmetic sequence that is explicit is

$a_n=a_1+d(n-1)$  where $a_1$ is the first term (so -1), and d is the common difference (-2). n is the number position in the sequence. As soon as we find the formula or model for this sequence we can find any number term we want. Filling in the formula:

$a_n=-1-2(n-1)$ and we'll clean that up just a bit:

$a_n=-1-2n+2$ (I just distributed through the parenthesis) and a bit more to

$a_n=-2n+1$ and if we want the 21st term, fill in a 21 for n:

$a_{21}=-2(21)+1$ and

$a_{21}=-42+1$ so

$a_{21}=-41$

Answer 2

Answer:

-55

Step-by-step explanation:

the sqeuence seems to be subtracting by 2 everytime.

so it will be -1,-3,-5,-7,-9,-11,-13,-15,-17,-19,-21,-23,-25,-27,-29..

the answer will be 27*-2(-54) -1(because we start at -1 , not 0)