This one comes courtesy of frequent commenter, John Friend. It is an example from Cambridge’s Mathematical Methods 34.

UPDATE (19/08/21)

It amazes me at times what does and does not concern some commenters. That’s not intended as a criticism. Well, it is, but it isn’t. And, it is. It’s complicated.

This one is old, which is not in keeping with the spirit of our PoSWWs and WitCHes. And, we’ve already written on it and talked about it. But, as the GOAT PoSWW, it really deserves its own post. It is an exercise from the textbook Heinemann Maths Zone 9 (2011), which does not appear to still exist. (And yes, the accompanying photo appeared alongside the question in the text book.)

Like the previous post, this one comes from Maths Quest Mathematical Methods 11, and is most definitely a WitCH. It can also been seen as a “contrast and compare” with WitCH 15.

Subsection 13.2.5, below, is on “differentiability”. The earlier part of chapter 13 gives a potted, and not error-free, introduction to limits and continuity, and Chapter 12 covers the “first principles” (limit) computation of polynomial derivatives. We’ve included the relevant “worked example”, and the relevant exercises and answers.

The following is just a dumb exercise, and so is probably more of a PoSWW. It seems so lemmingly stupid, however, that it comes around full cycle to be a WitCH. It is an exercise from Maths Quest Mathematical Methods 11. The exercise appears in a pre-calculus, CAS-permitted chapter, Cubic Polynomials. The suggested answers are (a) , and (b) 81/32 km.

Has it occurred to anyone else that these WitCHes are a blogging Ponzi scheme? As long as we keep posting new WitCHes, no one bugs us about not polishing off the old WitCHes. What the hell; we’ll keep going until someone calls the Blog Cops. And, to continue with the scheme, this WitCH comes from the Cambridge text Specialist Mathematics 1 & 2, in the section titled Linear Diophantine equations. Happy hunting.

Yes, we have tons of overdue homework for this blog, and we will start hacking into it. Really. But we’ll also try to keep the new posts ticking along.

The following, long WitCH comes from the Cambridge text Mathematical Methods 3 & 4 (including an exercise solution from the online version of the text).

UPDATE (07/02/21)

Commenter John Friend has noted a related question from the 2011 Methods Exam 1. We’ve added that question below, along with the discussion from the assessment report.

For a peculiar reason,* we have inherited a very nice collection of mathematics texts. They are mostly calculus/engineering texts and advanced applied mathematics, but there is a range, and there are a number of classics.

We are now looking for homes for these books. So, take a look at the photos below, and comment (or email me), indicating what you might like. Also feel free to pass on the offer to whomever you think might be interested. Here are the rules:

1) There are no rules: this is Calvinball. We’ll make it up as we go along.

2) The books are free, but you could consider making a donation to Tenderfeet. If you’re in Melbourne, we can arrange pick-up or drop-off, and otherwise I can mail the books, and we’ll figure out the postage somehow.

3) You can request as many or as few books/categories as you wish, with whatever levels of enthusiasm and specificity seem appropriate.

4) It is definitely not first come, first served. I’ll do my best to handle overlapping requests in a reasonable manner, with some preference given to starving students.

5) Would you like fries with that? If you express interest in a book, I might suggest similar books from the pile.

6) Most of the books should be identifiable from the photos, but feel free to ask for further details on any book. The books are roughly sorted into topics, so if you cannot identify a book, it’ll probably be similar in content to its neighbours.

7) See Rule 1.

Go for it, and thanks.

*) People are stupid.

UPDATE (06/01/21)

Thanks to everyone for contacting me. There are plenty of books still up for grabs, and people are still welcome to make requests. In a couple days, I’ll look to rationalise the requests thus far, and I’ll contact everyone to arrange the handovers.

UPDATE (09/01/21)

OK, I think I’ve replied to everyone who has requested books, to arrange pick-up/drop-off. If you think I missed you, please give me a nudge with a comment below. (There are still plenty of unclaimed books, particularly on mechanics, and modelling and the like.)

UPDATE (15/01/21)

OK, all the books have now been assigned. The plan is for one big Traveling Salesman tour of Melbourne on Wednesday 20/1. So, unless other arrangements have been discussed, please reply to my email to you, to confirm there’s a safe place to drop the books if need be.

FINAL UPDATE (04/02/21)

All done! All the books have been picked up or delivered or mailed. Along the way, it was great to meet, or re-meet, a bunch of you guys. (Hopefully the mailed books will arrive shortly, if they haven’t done so already. I’m sorry, but it was prohibitively expensive to mail them with tracking.)

Thanks to all of you who offered a home for these excellent but otherwise-God-knows-where books, and I hope they’ll be of interest and use. Thanks also, very much, to those who donated to Tenderfeet.