All answers are in the form of True/False with a explantion as to why: 1) An ideal band-pass filter centered (at ± 0) can be created by just multiplying the sinc function by cos(0t) in the the time domain. 2) Nyquist theorem deals with windowing of a signal in the time domain, which is translated into leakage in the frequency domain. 3) The global frequency response of an LTI system composed of two LTI systems in parallel with each other is simply the addition of the individual frequency responses of the systems. 4) We can find the H(j) of an unknown LTI system by stimulating it with a impulse and taking the Fourier Transform of its response. Another more realistic way is to stimulate the LTI system with a unit step function (signal), take the Fourier Transform of its response, multiply it by (j) for every 0 and divide it by pi at =0. ^I believe that one is true, but I am needing help forming an explanation. 5) A first step towards sampling an unknown analog signal without aliasing is to low-pass filter the signal. Solution 1) False Because fourier transform of sinc function is rectanctangular function in frequency domain, and fourier transform of cos function is impuse function. So when when multiply in time domain that means convoution in frequency domain. And if ve convolude rectangular function with impulse function then it would be rectangular pulse train. Which is not ideal band paas filter at w=0. 2) False It would be either window or leakage in time domain or frequency domain. 3) TRUE It is simply understand by block reduction method in control system. When there is another forward block we add both maid forward block with secondry forward block. OR LTI is linear in nature so add in parallel and multiply in series. 4) TRUE Its because the response or tansfer function of any system is called impulse response. It means when the input is Impuse function what is the output of that system. Same as the relation between unit imulse response and impuse respone in just fouries tranfer of unit step function. Because the fourier transform of impulse is unity. so if input is unit step function multiply it by (j) for every 0 and divide it by pi at =0.(1/(i)+(),) 5)FALSE Low paas filter use after sampling to recover the original signal..