### Home > AC > Chapter 11 > Lesson 11.1.2 > Problem11-23

11-23.

Marley thinks that the two lines below are perpendicular, but Bob thinks they are not. Who is correct and how do you know?

$2x − 7y = 16 \\7x + 2y = 3$

Rearrange the equations into slope intercept form. If the slopes
are opposite reciprocals of each other then the lines are perpendicular.