Let R be the region enclosed by the graphs of y = y = e-x, y = ex, and x = ln 4. Find the area of R by setting up and evaluating a definite integral. Set up, but do not integrate, an integral expression in terms of a single variable for the volume generated when the region R is revolved about the x-axis. Set up, but do not integrate, an integral expression in terms of a single variable for the volume generated when the region R is revolved about the y-axis.