The slope of a line perpendicular to other line is the negative reciprocal of the slope.
This means, if the slope of a line is x, the slope of a perpendicular line will be:
[tex]-\frac{1}{x}[/tex]
Then , the first thing we should do is to find the slope of f(x).
To find the slope of a line that passes two points P and Q we use:
[tex]\begin{gathered} \begin{cases}P=(x_p,y_p) \\ Q=(x_q,y_q)\end{cases} \\ \text{slope}=\frac{y_p-y_q}{x_p-x_q} \end{gathered}[/tex]
In this case, we can use P = (1, 4) and Q = (-3, 2)
Then:
[tex]\text{slope}=\frac{4-2}{1-(-3)}=\frac{2}{4}=\frac{1}{2}[/tex]
Now, we know that the slope of g(x) is perpendicular to f(x) which has a slope of 1/2
The reciprocal is:
[tex]\frac{1}{2}\Rightarrow\frac{2}{1}=2[/tex]
And to make it the negative, we multiply by (-1):
[tex]2\cdot(-1)=-2[/tex]
Thus, g(x) has a slope equal to -2
