Given the first five terms of the sequence 19, 15, 11, 7, 3 . . . , use subscript notation to describe a7 .

Answer 1

In subscript notation, we would describe the term $a_k$ as $a_k = 19 - 4(k-1)$.

Therefore, we can describe $a_7$ as $a_7 = 19 - 4(7-1) = 19 - 4(6) = 19 - 24 = \boxed{-5}$.