questions below:

Determine the values of r for which det (A - rI) = 0. 5 5 A = 6 12 (Simplify your answer. Use a comma to separate answers as needed.)Express the given system of higher-order differential equations as a matrix system in normal form. x"+ 4x + 3y = 0 y" - 2x = 0 Which of the following sets of definitions allows the given system to be written as an equivalent system in normal form using only the new variables? OA. X1 = X', X2 = y' OB. X1 =X', X2 =X"', X3 = y', X4 =y" O C. X1 = X, X2 =X', X3 = y, X4 = y' O D. X1 = X, X2 =X", X3 = y. XA =y" Write the system of equations using matrix notation. Select the correct choice below and fill in the answer box to complete your choice. (Type an exact answer.) X1 O A. X2 X1 X1 X2 O B. X2 Xa