Question

What type of slopes do parallel lines have? And, What type of slopes do perpendicular lines have?

Answer 1

parallel lines have the same slope

perpendicular lines have the negative reciprocal

ie 3--------> -1/3

Answer 2

The parallel lines have the same slope.

Let

$k:y=m_1x+b_1,\ l:y=m_2x+b_2\\\\l\ ||\ k\iff m_1=m_2$

Perpendicular lines have the negative and reciprocal slopes.

$l\ \perp\ k\iff m_1m_2=-1\to m_2=-\dfrac{1}{m_1}$