3. Two identical masses are connected to each other, and to a nearby wall, using a number of linear springs. The

variables and y denote the displacements of the masses from the wall relative to their positions when the

springs are relaxed, and m and k are constants. Which of the following constitute possible equations of motion

for this system?

(a) μä + 2kx = 3ky,

(b) μë + 2kx = 3ky,

pij +2ky = 4kx;

pÿj +2ky = 3kx;

(c) μä + 7kx = 7ky,

μÿ +7ky = 5kx;

(d) μä + 7kx = 5ky,

pÿj +5ky = 5kx.

If you reject the plausibility of any of these systems of equations, explain why.