Question

Write an
explicit formula for An, the nth term of the sequence 5,-1, -7,....

Answer 1

-6n + 11

Explanation:

The difference between each number is 6 (-6)

If n=1 then -6n + 11 =5

If n=2 the (-6×2) + 11 = -1

If n=3 the (-6×3) + 11 = -7

and so on.

You use the difference between each number to identify how much you need to times n by the you use that information and figure out how much you need to add / subtract to find the first number in the sequence. To check you do the same thing for the second number or third number.

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