(x) = -3x + 3. then f*-1(x)

The next term is 8/3.



the sequence is not arithmetic since all of the numbers are not being increased/decreased by a constant amount (a common difference).

but the sequence is geometric because there is a common ratio. the ratio between the second term and the previous is the same as the ratio between the third term and the previous.

    ratio = second / first = 6 / 9 = 2/3
    ratio = third / second = 4 / 6 = 2/3

the terms share a common ratio; you multiply each term by 2/3 to get the next term.

    9 times 2/3 is 6.
    6 times 2/3 is 4.

continuing this pattern, 4 times 2/3 is 8/3.

the next term is 8/3.