Question 712528
Where does the function cross the horizontal axis?  What are the zeros of the function?  Does it have REAL zeros?  What is the value of the discriminant?  


x^2+8x+16>=0
So can this be factored?  (x+4)(x+4)>=0, seems to have a zero at x=-4.  That is where the quadratic will be zero.  What about x<-4, and x>-4?  NO PART OF THE FUNCTION IS LESS THAN ZERO.  The graph opens upward, has a vertex which is a minimum and touches the horizontal axis.  


So you want to show work?  Remember vertex at (-4,0).  Pick any x value less than -4.  Is x+4 positive or negative?  Negative! so (-)(-)=(+), so above the horizontal axis.  Pick any x value greater than -4.  Is x+4 positive or negative? Positive!  so (+)(+)=(+), and above the horizontal axis. Just pick examples and show them.