If the official manual is inaccessible, consider these next-best resources:
Don't skip shifting, scaling, and inverting—they are the building blocks for convolution and DTFTs later on. Signals Systems And Transforms 5th Edition Solutions Manual
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One of the hardest hurdles in this course is keeping track of the differences between Continuous-Time Signals ($x(t)$) and Discrete-Time Signals ($x[n]$). If the official manual is inaccessible, consider these
Practical and computational aspects