The following are the impulse responses of discrete-time LTI systems. Determine whether each system is causal and/or stable. Justify your answer a.  h[n]=(1/5)nu[n]h[n]=(1/5)^n u[n]

b. h[n]=(0.8)nu[n+2]

c. h[n]=(½)nu[−n]

d. h[n]=(5)nu[3−n]

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.