Analyze the beam using Stiffness Method

$($Assume $A$ is fixed, $B$ and $C$ are rollers; take $E=200$GPa,$I=200({10}^6)m{m}^4)$

Assemble the $K$ matrix and construct $Q=K*D+Q_{\text{F}\text{E}\text{R}}$ equation. Partition this equation into submatrices to find $D_u$ and $Q_{\text{s}\text{u}\text{p}\text{p}\text{o}\text{r}\text{t}\text{r}\text{e}\text{c}\text{t}\text{i}\text{o}\text{n}\text{s}}$

Find unknown displacements $D_u.$

Find Support Reactions and show them on free$-$body diagram of the beam.

Find Member$-$End$-$Forces using $q=k*d+q_0$ and show them on member free body diagrams

Draw shear and moment diagrams