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9 votes
9 votes
Can she get some help

Can she get some help-example-1
User Nof
by
2.8k points

2 Answers

23 votes
23 votes

Answer:

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

User Smartmic
by
2.8k points
21 votes
21 votes

Answer:

-55

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)

User LHWizard
by
3.2k points