Question

составьте формулу n-го члена последовательности:0,7,26,63,124...0,2,8,26,80...1,2,4,8,16...

Answer 1

1) 1³-1=0, 2³-1=7, 3³-1=26, 4³-1=63, 5³-1=124,.... т.е. a[n]=n³-1.
2) 3⁰-1=0, 3¹-1=2, 3²-1=8, 3³-1=26, 3⁴-1=80,... т.е. a[n]=3ⁿ-1.
3) 2⁰=1, 2¹=2, 2²=4, 2³=8, 2⁴=16,... т.е. a[n]=2ⁿ.