Question 155519
OK, let's pick a range from -5 to 5.
From (-5,-2), the function is 
{{{f[1](x)=x/2-5}}}
From (-2,5), the function is 
{{{f[2](x)=5x+4}}}
Since for a straight line, we only need two points we will use -5,-2,and 5. 
{{{f[1](-5)=-5/2-5=-15/2}}}
{{{f[1](-2)=-2/2-5=-6}}}
Plot those two points, (-5,-15/2) and (-2,-6) and draw the straight line connecting them.
{{{drawing( 300, 300, -5, 5, -10, 10,grid( 1 ),circle( -5, -7.5, .1 ),circle(-2,-6,.1),green(line( -5, -7.5, -2, -6)))}}}
Next,
{{{f[2](-2)=5(-2)+4=-6}}}
{{{f[2](5)=5(5)+4=29}}}
Plot those and connect those points. 
Note the change in scale of the graph. 
{{{drawing( 300, 300, -5, 5, -30, 30,grid( 1 ),circle(5,29,0.1),circle( -5, -7.5, .1 ),circle(-2,-6,.1),blue(line(-2,-6,5,29)),green(line( -5, -7.5, -2, -6)))}}}