Question

Write the equation of a line in slope-intercept form that is perpendicular to the line y = 3/5 = 1 and passes through the point (-9, 4).

Answer 1

The slope of the line $y=\frac{3}{5} x-1$ is $m=\frac{3}{5}$.

The line perpendicular to the above line has slope $-\frac{1}{m} =-\frac{5}{3}$

Its equation is $y=-\frac{5}{3} x+c$. Since this line passes through, $(-9,4)$,

$4=-\frac{5}{3} )(-9)+c\\ c=-11$

Thus the equation of the line in slope intercept form is $y=-\frac{5}{3} x-11$