On 0≤x≤5 a solid has cross sections perpendicular to the x-axis. For 0≤x<2 the cross sections are squares whose side length is 4−x units. For 2≤x≤5 the cross sections are rectangles whose height is x−1 units and whose width is the constant k units. Determine the value of k that makes the cross-sectional area continuous at x=2.