1 .
The function $f: \mathbb{N} \rightarrow \mathbb{N}$ is defined by
$$
\begin{align}
f(0) &= 15 \\
f(n) &= f(n - 1) +6n - 4\; \ \mathrm{for}\ n \geq 1
\end{align}
$$
What is $f(n)$?
(a)
$f(n) = 3n^{2} - 2n + 15$
(b)
$f(n) = 3n^{2} + n + 15$
(c)
$f(n) = 3n^{2} + 2n + 15$
(d)
$f(n) = 3n^{2} - n + 15$