Question 249110
Hello, 
First, let's set these equations up like this:
y=-1/2x-11
y=2x+4
Notice that these now show the slope of the line with -1/2x and 2x.
Since these are the reciprocal of each other and one is negative, the lines are perpendicular to each other. 
RJ Toftness
www.math-unlock.com