Describe Variables in detail. Give examples

Idon understand these and need some ! ?

Least square fit to polynomial write a function leastsquarefit3pol that solves a linear system of equations to find a least squares fit of a third order polynomial to an experimental data set given as two row arrays. the function leastsquarefit3pol must explicitly solve a set of linear equations and cannot use polyfit. there should be no restriction on the size of the problem that can be solved.

What is domain name system (dns)? allows dynamic ip address allocation so users do not have to have a preconfigured ip address to use the network converts ip addresses into domains, or identifying labels that use a variety of recognizable naming conventions the efficient coexistence of telephone, video, and data communication within a single network, offering convenience and flexibility not possible with separate infrastructures the integration of communication channels into a single service