The functions and and their tangent lines at are shown in the figure below.
graph of f, a concave down function with positive slope, in blue; g, a concave up function with negative slope, in black, both of which pass through the point (4,0), and their tangent lines, graphed in red and green, respectively.

is shown in blue, in black, and the tangent line to is , and is graphed in red, and the tangent line to is , and is graphed in green.

Find the limit