The impulse response h(t) of a linear time-invariant continuous time system is described by h(t)=exp(αt)u(t)+exp(βt)u(−t), where u(t) denotes the unit step function, and αandβ are real constants . This system is stable if
A
α is negative and β is negative
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B
α is positive and β is negative
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C
α is positive and β is positive
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D
α is negative and β is positive
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Solution
The correct option is D α is negative and β is positive h(t)=eαtu(t)+eβtu(−t)
For the system to be stable,∞∫−∞h(t)dt<∞
For the above condition, h(t) should be as shown below.