How do you graph (2x)/(x-4)2xx4?

1 Answer
Jul 31, 2015

Graph as y = (2x)/(x-4)y=2xx4
by establishing a few data points with random values of xx and noting the asymptotic limits at y=2y=2 and x=4x=4

Explanation:

The asymptotic limit x=4x=4 should be obvious from the expression (since division by 0 is undefined).

y=(2x)/(x-4)y=2xx4 is equivalent to y=2/(1-4/x)y=214x [provided we ignore the special case x=0x=0]
As x rarr +-oox±
color(white)("XXXX")XXXX4/x rarr 04x0
and
color(white)("XXXX")XXXXy=2/(1-4/x) rarr 2/1 = 2y=214x21=2
giving the horizontal asymptotic limit.

A few test values for xx, such as
color(white)("XXXX")XXXXx=0 rarr y=0x=0y=0
color(white)("XXXX")XXXXx=2 rarr y = -2x=2y=2
color(white)("XXXX")XXXXx=5 rarr y=10x=5y=10
color(white)("XXXX")XXXXx=-4 rarr y = -1x=4y=1
help give shape to the graph

graph{(2x)/(x-4) [-25.3, 26, -11.27, 14.4]}