V and I are sources of constant voltage and current whose values are 5V and 1mA, respectively. R1 = 16k ohm;R4 = 95k ohm.

The keys are switched in two instants of time: t = 0 and t = t₁.

t₁ is greater than 5 times any time constant involved in the circuit, i.e., t₁ = 5 * Cany

When t= 0¯:

S1 and S4 keys are opened;

S2 and S3 are closed.

The key's states when 0 < t₁ and t> t₁ are defined below:

The table below describes the value and nature of components X₁ to X4; Y₁ to Y4; E and D.

Where first letter represents the nature of elements, being:

C is capacitor, R is resistor, L is inductor. The value is between parenthesis.

SC means short circuit and OC means opened circuit.

Determine:

a) What is the value of the voltage at R with the polarity indicated in the figure when t = 0+ and t=0¯?

b) What is the voltage value at R with the polarity indicated in the figure when t = t₁+ and t = t₁¯?

c) What is the voltage value at R with the polarity indicated in the figure when t → ∞ ?

d) The expression for the voltage at R with the polarity indicated in the figure i.e., v(t) for 0 < t