A linear equation is drawn as a straight line on a set of axes. To draw the graph we need coordinates. We generate these coordinates by substituting values into the linear equation.

Least squares regression equations The premise of a regression model is to examine the impact of one or more independent variables (in this case time spent writing an essay) on a dependent variable of ...

While I do spend lots of time pushing the idea of linear approximations on my students, we do need nonlinear functions to describe most interesting physical phenomena.