Quiescent implies i1, i2 and their derivatives are zero for t = 0, ie

i1(0) = i2(0) = i1'(0) = i2'(0) = 0.


For loop 1:
MATH

For loop 2:


MATH

Substituting our result from (1) gives:
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Taking Laplace transform:


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Let MATH

So $20=A(s+250)+Bs$

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MATH

So MATH

Taking Inverse Laplace:

So MATH

10_lap_app5_18pt__17.png