how to find the next three terms in the sequence

Question

1) 1,-3,9,-27,8,...

2) 0,3,8,15,24,...

3) 14,34,54,74,94,...

Answer 1

1) (-3)^(n-1) for n=1,2,3,4,5,...

    (-3)^(6-1)=(-3)⁵=-243

    next would be 729 and then -2187

 

2) n²-1 for n=1,2,3,4,5,...

    6²-1=36-1=35

    next would be 48 and then 63

 

3) 20n-6 for n=1,2,3,4,5,...

    20(6)-6=120-6=114

    next would be 134 and then 154