Exam Questions Papers - Engineering

Q1:

The impulse response h(t) of a linear time-invariant continuous time system is described by h(t) = exp (atu(t) + exp (βtu (- t), where u(t) denotes the unit step function, and a and β are constants. This system is stable if

A a is positive and β is positive

B a is negative and β is negative

C a is positive and β is negative

D a is negative and β is positive

ANS:D - a is negative and β is positive

h(t) = e+atu(t) + eβtu(- t) For h(t) to be stableh(t) dt < ∞ It will happen when a is negative and β is positive.