Question

What is the explicit formula for this sequence-15, -18, -21, -24,...

Answer 1

Answer: The explicit formula for the following sequence is:

`-15,-18,-21,-24`

According to the pattern in the sequence, the explicit formula is as follows:

`\begin{gathered} a_n=-15-3(n-1) \\ \\ a_n=-15-3n+3 \\ \\ a_n=-12-3n \\ \\ \therefore\rightarrow \\ \\ a_n=-12-3n=-15+(n-1)(-3) \\ \\ a_n=-15+(n-1)(-3) \end{gathered}`

Therefore the answer is Option(2).