# Confused on a Parallel and Perpendicular Line question?

It says: for what value of k are the two lines 2x+ky=3 and x+y+1 a) parallel? b) perpendicular?

Update:

the second equation is actually x+y=1

### 1 Answer

Relevance

- TomVLv 78 years agoBest Answer
If two lines are parallel, their slopes are equal. If two lines are parallel, the product of their slopes is equal to -1.

Line1: 2x+ky = 3 : in slope-intercept form: y = -(2/k)x + 3/k : slope = -2/k

Line2: x+y = 1 : in slope-intercept form: y = -x + 1 : slope = -1

Line 1 is parallel to Line 2 if their slopes are equal: -2/k = -1 ==> k = 2

Line 1 is perpendicular to line 2 if (-2/k)*(-1) = -1 ==> k = -2

Still have questions? Get your answers by asking now.