Problem #$2$: Using the slope$-$deflection method, determine the internal moments at joints $A,B,C,$ and $D$ in the frame below $($i$.$e$.,$ there is no need to draw the entire moment diagram$).$ Assume $EI$ is constant. The base supports are both fixed.

Hints$/$Notes:

Feel free to use the Excel file provided or your calculator to perform matrix math.

For the joint force equilibrium equation, be careful with the FBD of column $AB-$ don't forget there is load applied directly to the column!