Question 888100
<pre>
It does not have any zeros,

Since cos(4x)is always between -1 and +1, the first term has smallest
positive velue when cos(4x) = 1 which gives {{{y=12/1+4=16}}}, so 16
is the minimum positive value.  The first term has largest negative value 
when cos(4x) = 1 which gives {{{y=12/(-1)1+4=-8}}}, so -8 is the maximum 
negative value.  The graph never crosses the x-axis and thus there are
no zeros at all.

{{{drawing(800,300,-.2,6.3,-25,25,graph(800,300,-.2,6.3,-25,25,12/cos(4x)+4),
locate(.1,16,(matrix(1,3,0,",",16))),locate(.5,-3,(matrix(1,3,pi/4,",",-8))),

circle(0,16,0.03),circle(0,16,0.01),
circle(pi/4,-8,0.03),circle(pi/4,-8,0.01)




)}}}

Edwin</pre>