You can put this solution on YOUR website! Find the roots.
root at x = 4 and x = -4
Now pick a value less than -4. let's say -10.
When x=-10, then which is > 0
Pick a value between the two root. Say x=0
When x=0 which is < 0
Pick a value greater than 4, say 10
Again which is greater than 0.
So points to the left of -4 and to the right of 4 do not satisfy the inequality.
The plot will be all points above the curve x^2-16 and below the x axis, between -4 and 4
See this URL for a plot
http://www.wolframalpha.com/input/?i=x^2-16%3C%3D0
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