Answer: Choice D)
F(x) > 0 over the inverval (-infinity, -4)
Translation: The y or f(x) values are positive whenever x < -4.
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Further Explanation:
Recall that y = f(x), so if we say something like f(x) < 0 then we mean y < 0. Choice A is false because points on the curve to the left of x = -4 have positive y coordinates. Similar reasoning applies to choice B as well.
Choice C is false because while the interval (-infinity, -4) is above the x axis, the portion from x = -4 to x = -3 is below the x axis.
Choice D is true because everything to the left of x = -4 is above the x axis. Pick any point on the blue curve that is to the left of x = -4. This point will be above the horizontal x axis. Keep in mind that the parenthesis notation attached to the -4 means we dont include -4 as part of the interval.
