Linear Algebra and Calculus are different, and each is as hard as the course designer chooses to make it!

AoPS is accredited now, by the Western Association of Schools and Colleges, if that helps. Academically, the idea that one of its courses isn't as good as the corresponding course taken in a bricks and mortar school is laughable. I suppose it could be an issue that there's no invigilated final exam, but that seems to be common.

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