13. The characteristic equation is:

a. q s( ) = + s s 3 2 5 1 − − 0 6 s 

b. q s( ) = + s s 3 2 5 1 + + 0 5 s 

c. q s( ) = − s s 3 2 5 1 + − 0 5 s 

d. q s( ) = − s s 2 5 1 + 0

In Problems 13 and 14, consider the system represented in a state-space form 0 0 1 0 x = 0 0 1 x+ 0 u -5-10-5 20 y= [101] x