Find a recursive formula for the sequence: 1, -1,-7,-25

Check the forward differences:

-1 - 1 = -2

-7 - (-1) = -6

-25 - (-7) = -18

Notice how the differences appear to follow a geometric progression with common ratio 3. So if denotes the th term in the given sequence, we seem to have

so that the general pattern for would be

Then the sequence is given recursively by

The first 10 terms in the sequence would be

1, -1, -7, -25, -79, -241, -727, -2185, -6559, -19681

£56

step-by-step explanation: