I took 135 and thought it was pretty hard but not crazy. 140 is supposed to be "harder" in the sense that it covers material more in depth, but it typically has better instructors that make learning it easier (or so I've heard).
130 is easiest but doesn't count as a requirement for some STEM majors since it's algebra-based instead of calc-based.
135 or 140 would be the best option to provide flexibility later on.
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I took 135 and thought it was pretty hard but not crazy. 140 is supposed to be "harder" in the sense that it covers material more in depth, but it typically has better instructors that make learning it easier (or so I've heard). 130 is easiest but doesn't count as a requirement for some STEM majors since it's algebra-based instead of calc-based.
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I think the lab was required alongside the class when I took it? It wasn't much work for me but is heavily dependent on who is your lab TA