Why do we allow electronic instruments to warm-up before use?

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.

Which feature is selected to practice and save the timing of a presentation

An npn transistor is correctly biased and turned on if the a. base is negative. b. collector is negative. c. collector is positive with respect to the emitter and negative with respect to the base. d. collector is the most positive lead followed by the base.