Solve Transient Analysis Problem: Find I0

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i was trying to solve this question(file attached), but i can only come up with the answer:

i assumed i_L=0 at t=0, hence arrived at this:

I_L(t) = 6mA(1 - exp(-100000t))

i can't figure out how I_o came about.

can someone come it my rescue and tell me how the I₀ came into play.

Kind Regards,

 

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anyone to help?