Question

What is the y-intercept of the equation of the line that is perpendicular to the line y=3/5x+10 and passes through the point (15,5)A) y=3/5x-20B) y= -3/5x+20C) y= 5/3x-30D) y=-5/3x+20

Answer 1

Two lines are perpendicular if the multiplication of their slopes is equal to -1.

The slope of y=3/5x+10 is 3/5. Then a line perpendicular will have the next slope:

$\begin{gathered} m\cdot\frac{3}{5}=-1 \\ m=-1\cdot\frac{5}{3} \\ m=-\frac{5}{3} \end{gathered}$

The only possible answer with this slope is:

D) y=-5/3x+20​

which has a y-intercept of 20