Question 696445
 Parallel Lines and Their Slopes
{{{m[1]=m[2]}}}

In other words, the{{{ slopes}}} of{{{ parallel }}}lines are {{{equal}}}.


Perpendicular Lines and Their Slopes 

{{{m[1]=-1/m[2]}}}

In other words, perpendicular slopes are negative reciprocals of each other.


Slope/Intercept Equation of a Line

{{{y=mx+b}}}

where {{{m}}} represents the {{{slope}}} and {{{b}}} represents the {{{y-intercept}}}


example:

{{{y=4x-1}}}...=> ... {{{m=4}}} and {{{b=-1}}} 

parallel line will be

{{{y=4x+1}}}....=> ... {{{m=4}}} and {{{b=1}}}

perpendicular line will be

{{{y=-(1/4)x-1}}}....=> ... {{{m=-1/4}}} and {{{b=-1}}} 


see all three on a graph:

{{{ graph( 600, 600, -10, 10, -10, 10, 4x-1, 4x+1,-(1/4)x-1) }}}


{{{y=4x-1}}}...red

{{{y=4x+1}}}......green

{{{y=-(1/4)x-1}}}....blue