[M] Compute the stiffness matrix D–1 for D in Exercise 39. List the forces needed to produce a deflection of .04 in. at point 3, with zero deflections at the other points.Exercise 39:[M] Let be a flexibility matrix, with flexibility measured in inches per pound. Suppose that forces of 40, 50, and 30 lb are applied at points 1, 2, and 3, respectively, in Fig. 1 of Example 3. Find the corresponding deflections.Fig. 1 of Example 3:

Solution:-Step1Given that Let be a flexibility matrix, with flexibility measured in inches per pound. Suppose that forces of 40, 50, and 30 lb are applied at points 1, 2, and 3, respectivelyStep2To findList the forces needed to produce a deflection of .04 in. at point 3, with zero deflections at the other points.Step3We have Now= We know thatDf= f= = = = = Forces must be 0,-1.3332,4 at points 1.2.3.Therefore, the forces 0,-1.3332,4 needed to produce a deflection of .04 in. at point 3, with zero deflections at the other points.