An equation of the line with slope $4$ and containing the point $( 1,2)$ can be found by using the point-slope form with $m=4$, $x_{1}=1$, and $y_{1}=2$. $$\begin{array}{lrcll@{{16pt}}ll} & y-y_{1}&=&m( x-x_{1}) & & {\color{#0066A7}{\hbox{Point-slope form of a line}}} & \\[3pt] & y-2&=&4( x-1) & & {\color{#0066A7}{{m=4}\hbox{, }{x}_{1}{=1} \hbox{, }{y}_{1}{=2}}} & \\[3pt] \,\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ & ~\ \ \ \ \ y&=&4x-2 & & {\color{#0066A7}{\hbox{ Solve for }{y.}}} & \hbox{ } \end{array}$$

Figure 28 $y=4x-2$

See Figure 28 for the graph of $y$.