253.  The unit impulse response of a system is given as c(t) = -4e-t + 6e-2t. The step response of the same system for t > 0 is equal to
A. -3e-2t + 4e-t ? 1
B. _3e-2t 4e-t _
C.(e) _3e-2t ? 4e-t ? 1
D.+ 4e-t - 1

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254.  A 5x7 matrix has all its entries equal to -1. The rank of the matrix is
A.7
B.5
C.1
D. zero

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255.  The eigen-values of the matrix are
A.(a) (a + 1), 0
B. a, 0
C.(c) (a - I), 0
D. 0, 0

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256.  The impulse response of an initially relaxed linear system is e-2t U(t). To produce a response of t e-2t U(t), the input must be equal to
A. 2 et U(t)
B. ? ,U(t)
C. e-2t U(t)
D. e-t U(t)

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257.  The closed-loop transfer function of a control system is given by C (s) =2 (s - I),R (s)=(s + 2) (s + 1) For a unit step input the output is
A. -3 e-2t + 4 e-t ? I
B. -3 e-2t - 4 e-t + 1
C. zero
D. infinity

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258.  A system equation XX where A =Transfer function
A.cos t
B.1
C. ?r? sin t
D.sin 1

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259.  The unit-impulse response of a unit-feedback control system is given by c(t) = -te-t + 3 et, (t,0)
A. s2 + 5s + 7
B. s2 + 5s + 7
C. S2 + 3s + 2
D. s2 + 3s + 2

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