Question 957400
let take an example:

 graph  {{{k(x) = x^3}}}

{{{ graph( 600, 600, -10, 10, -10, 10, x^3) }}}


now, pay good attention what will happen if I put {{{-x}}} in for {{{x}}}: 
 
{{{k(-x) =(-x)^3= -x^3}}}

see it on a graph:

{{{ graph( 600, 600, -10, 10, -10, 10, -x^3) }}}

This transformation rotated the original graph around the {{{y-axis}}}. Any points on the {{{y-axis}}} stay on the {{{y-axis}}}; it's the points off the axis that switch sides. This is always true: 

{{{k(-x)}}} is the {{{mirror}}}{{{ image}}} of {{{k(x)}}}, as reflected in the y-axis. 

see both on a graph:

{{{ graph( 600, 600, -10, 10, -10, 10,x^3, -x^3) }}}