The original propped cantilever beam can
be split into two cantilever beam cases:
case 1 – cantilever beam with uniform load
case 2 – cantilever beam with concentrated load at the tip
Our approach here is to first remove the roller support at A, making the beam a cantilever (i.e., a statically determinate beam). To replace the roller support, we add a second case that consists of an unknown concentrated force RA acting upwards on the beam at the tip of the cantilever.