9.- an = 16 + (n - 1)(-0.5)
n = 15
an = 16 + (16 - 1)(-0.5)
= 16 + 15(-0.5)
= 16 - 7.5
= 8.5
10.- an = 6 + (n - 1)(3)
n = 32
an = 6 + (32 - 1)(3)
an = 6 + (31)(3)
an = 6 + 93
an = 99
11.- -8, -6, -4, -2,
n = 100
Sequence an = -8 - (n + 1)
an = -8 - (100 + 1)
an = -8 - 101
an = -109