Circuit convention

In eehelp3 file or the CRT, book says or used negative signs, but one tutor says its positive. Who is right and why? In eehelp4 please make sure graphs are ok according to data, and with my sign convention problems what is energy absorbed, received, released....lost..how tie in with sign conventions etc and the circuit elements. Picture might help me or one in these examples

Sign convention for power in an electrical circuit

Please refer attachment.

Dynamic Circuit

(See attached file for full problem description)

Time response for unit step input

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The figure to the left is a voltage source...

See diagram in attache file. --- The figure to the left is a voltage source The figure on top us a resistor(Ri ) but its part of the source. The figure to the right is a resistor ( R ) (outside the source) 1. What is the largest power that can be delivered to the load R? 2. What value of R achieves that?