Which among the following are the stable discrete time systems?

1. y(n) = x(4n)
2. y(n) = x(-n)
3. y(n) = ax(n) + 8
4. y(n) = cos x(n)

Which property of delta function indicates the equality between the area under the product of function with shifted impulse and the value of function located at unit impulse instant?

A. Replication

B. Sampling

C. Scaling

D. Product

Which among the below specified conditions/cases of discrete time in terms of real constant 'a', represents the double-sided decaying exponential signal?

A. a > 1

B. 0 < a < 1

C. a < -1

D. -1 < a < 0

Damped sinusoids are _____

A. sinusoid signals multiplied by growing exponentials

B. sinusoid signals divided by growing exponentials

C. sinusoid signals multiplied by decaying exponentials

D. sinusoid signals divided by decaying exponentials

An amplitude of sinc function that passes through zero at multiple values of an independent variable 'x' ______

A. Decreases with an increase in the magnitude of an independent variable (x)

B. Increases with an increase in the magnitude of an independent variable (x)

C. Always remains constant irrespective of variation in magnitude of 'x'

D. Cannot be defined

A system is said to be shift invariant only if______

A. a shift in the input signal also results in the corresponding shift in the output

B. a shift in the input signal does not exhibit the corresponding shift in the output

C. a shifting level does not vary in an input as well as output

D. a shifting at input does not affect the output