Books that are designed to be a self-teaching manual must be mathematically clear and grammatically accurate. Unfortunately, in this case, while the mathematics is easily understandable, the English is often stiff and there are many grammatical errors. For example, on page 12 of “Conics 1 Part 1” there are the sentences “Those lines are lines vertical.” and “In short, a line vertical has no slope.” The question then becomes, “Does the lower quality of the English detract enough to render the books invalid as self-teaching aids?” The answer is that it does lower the quality but not to the level where they are unusable.
The material covered in the books is:
Each book opens with a section of explanation of the subject. This is followed by a list of example problems and then suggestions or solutions to those problems.
The books are meant to be short primers to selected topics in precalculus and the mathematics is sound and topical. In my experience, mathematical beginners can become extremely frustrated by anything they perceive as a flaw, so the best I can say about these books is a qualified, “It is possible to use them to learn the material.”
Charles Ashbacher splits his time between consulting with industry in projects involving math and computers, teaching college classes and co-editing The Journal of Recreational Mathematics. In his spare time, he reads about these things and helps his daughter in her lawn care business.