### Home > CC4 > Chapter 7 > Lesson 7.2.2 > Problem 7-104

7-104.

Without graphing, determine which of the following equations represents lines that are parallel to each other. Which are perpendicular? Show how you know. Homework Help ✎

a.

–3

*x*+*y*= 5b.

–5

*x*+*y*= 3c.

*x*+ 5*y*= –15d.

–15

*x*+ 5*y*= –25

Put each equation into slope-intercept form

(*y* = *mx* + *b*, where *m* is the slope and *b* is the *y*-intercept). That means to solve for *y*.

Compare the slopes. If they are equal then they are parallel.

If they are the negative reciprocal of each other then they are perpendicular,