In the context of of cubic interpolation as discussed in the lecture, in order to find the cubic interpolating line one must

use parsimonious methods

solve a linear system where the unknow variable is time.

must solve a linear system in two equations a two varibles.

select four rates.

solve a cubic system.

solve a cubic system of four equations in four variable where the unknown is time

select two rates

find the slope and the intercept of the interpolating line

approximate the term structure