Large integration problem with messy output

Questions
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1

I have a large integration problem via the PDF function. I wish to have a resultant PDF function with total area under to the curve equal to 1, and the parameter “t” should be on the 0 <= t <= 1 interval.

My worksheet is attached. Why I am being given a “Sequence” is a mystery to me.

My big question is … are there any Assumptions I can make to have the result the be a function of “t” on the 0 <= t <= 1 interval, with a total area under the curve be equal to 1?

Open in Wolfram Cloud ↗
2

According to the documentation, Evaluate does not take options. Try

Assuming[t <= 1, PDF[de, t]]