Question

The line given by the equation y=5x+2 is perpendicular to the line given by which of the equations below?

Answer 1

perpendicular lies have negative reciprocal slopes

M=5  so m=-1/5

Choice D

Answer 2

D

the equation of a line in slope-intercept form is

y = mx + c ( m is the slope and c the y-intercept )

y = 5x + 2 is in this form with m = 5

Given a line with slope m then the slope of a line perpendicular to it is

perpendicular slope = - $\frac{1}{m}$ = - $\frac{1}{5}$

the only equation from the list with this slope is equation D