Question

Which statement is true about the graphs of the two lines and ?

The lines are perpendicular to each other because –8 and are opposite reciprocals of each other.
The lines are perpendicular to each other because and are opposite reciprocals of each other.
The lines are neither parallel nor perpendicular to each other because –8 and are not opposite reciprocals of each other.
The lines are neither parallel nor perpendicular to each other because and are not opposite reciprocals of each other.

Answer 1

They are perpendicular. The slopes are −8 and 1/8, and −8 · (1/8) = −1, so the slopes are negative reciprocals. Thus the correct statement is: "The lines are perpendicular to each other because −8 and 1/8 are opposite reciprocals of each other."