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33 votes
33 votes
Can someone please help with this ?

Can someone please help with this ?-example-1
User Sadeghbayan
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1 Answer

29 votes
29 votes

Answer: -9n+20

This is the same as 20-9n

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Step-by-step explanation:

The jump from 11 to 2 is "minus 9"

The jump from 2 to -7 is also "minus 9".

Assuming this pattern continues on, we have an arithmetic sequence with

  • a = 11 = first term
  • d = -9 = common difference

The nth term can be found like so


a_n = a + d(n-1)\\\\a_n = 11 + (-9)(n-1)\\\\a_n = 11 -9n + 9\\\\a_n = -9n+20\\\\

Let's check the answer by trying n = 3


a_n = -9n+20\\\\a_3 = -9*3+20\\\\a_3 = -27+20\\\\a_3 = -7\\\\

This shows the third term is -7, which matches what the original sequence shows. The answer is partially confirmed. I'll let you check the other values of n. You should get 11 when trying n = 1, and you should get 2 when trying n = 2.

User Yngvar Natland
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