Suppose f (0) = 9, f ′(0) = 2, and f ″(0) = -4. If df is used to approximate Δf when Δx = 0.01, which of the following would be true?
df < Δf
df > Δf
df = Δf
f" < 0 indicates it is concave down.
f' > 0 means that the graph is rising.
So, an example would be a parabola which opens downward.
So, the tangent line at x=0 will be above the curve.
draw a graph and it should be clear now.