Use iteration to guess an explicit formula for the sequence. Use formulas from Section

$5\mathrm{.}2$ to simplify your answers whenever possible.

$t_k=t_{k-1}+3k,$ for every integer $k1$

$t_0=2$

$f_k=f_{k-1}+2*3^{k-1},$ for every integer $k2$

$f_1=1$