$2\mathrm{.}1$ It is required to reproduce the graph shown in Figure $2\mathrm{.}1$ of the text. The curves should be drawn from a sufficiently large number of calculated points that a smooth curve is obtained in each case. Print your graph in landscape mode and adjust its size so that the size of one unit in the $x$ direction corresponds to the size of one unit in the $y$ direction. Also, make the range and the grid lines in both the $x$ and $y$ directions correspond to those presented in Figure $2\mathrm{.}1$ of the text and make the diagram "fill" a regular$-$size sheet of paper.