It&#x27;s obviously just one guy&#x27;s screwup, but it got me thinking.<p>For first-year university subjects, there&#x27;s a smallish number of textbooks across the globe. For first-year physics, you&#x27;re using Halliday and Resnick, or ... a half-dozen or so others whose names escape me right now. But the point is that a small number of decent textbooks exist, and they tailor the courses to the textbooks.<p>The existence of a &quot;Texas high school math text&quot; makes me think that at the K-12 level, textbooks are tailored to the courses instead of vice versa. So you&#x27;ve got second-rate authors writing textbooks just for one market (admittedly Texas public schools is a big market that most authors would be very happy to have a monopoly over) and it makes it more likely that errors like this will slip through.<p>Calculus is the same the world over, it doesn&#x27;t make sense for Texas to have a different textbook to Toronto or Toowoomba.