OpenStax · 2016
Calculus Volume 1.
Ask what the limit is doing there.
The hard part of calculus is rarely the algebra — it is what a definition is for, and why the book introduces it where it does. Ask that in words, and the answer comes back with the passage that makes the case.
When the book does not answer your question, it tells you so instead of inventing an answer.
No account, no card. A Preview of Calculus, open in the browser.
Notation read exactly as written
This book’s equations come from the publisher’s own markup, so a fraction is a fraction and a subscript stays a subscript.
Answers from the section you are working in
Ask about a preview of the derivative and you are not answered with a technique three chapters ahead that assumes it.
Worked examples you can interrogate
Ask why a step is allowed, and the answer points at the passage that justifies it rather than asserting it.
Things worth asking this book
Each answer quotes the passage it came from and links to where it sits in the text.
- “What problem were tangent lines invented to solve?”
- “Why does the area problem belong in the same chapter as the tangent problem?”
- “What is a secant line approximating, and how badly?”
- “Where does this section say a limit is necessary rather than convenient?”
Questions people actually ask
- Can I try this one first?
- Yes — section 2.1, A Preview of Calculus, is open at /demo with no sign-in.
- Will it just give me the homework answers?
- It answers what the book says, with the passage attached. Where the book does not contain the answer, it declines — so it is a poor cheating tool and a good reading one.
- Are the equations reliable?
- In this book, yes: they are read from the publisher’s markup rather than recovered by OCR. That guarantee belongs to EPUBs and clean sources, not to scans.
It works the same on a novel
Citations, honest refusals and the vocabulary builder are not a science feature. They do as much for a Victorian novel as for a problem set.
- Pride and Prejudice — Jane Austen
- Frankenstein — Mary Shelley
- Alice's Adventures in Wonderland — Lewis Carroll
What it does not do yet
You have been sold AI reading tools before. Here is where this one is weak, so you can decide before you spend an evening on it.
- Equations in this book are exact. In a scanned PDF they come from OCR, where a fraction can occasionally come out wrong — check a formula before relying on it.
- It explains what the book says. It does not grade your work or confirm an answer the book does not contain.
- It runs in a browser, on a phone or a laptop. There is no native app yet.
- Highlights and notes export to Notion, Obsidian, Markdown or JSON. Generated study material does not export yet.
- It is a private beta. Things break, and the deal is that you tell me when they do.
Free Pro through the end of the year
The first 50 invitations include free Pro through the end of the year. Invitations go out in small batches so I can actually talk to everyone. Tell me what you are trying to read and I will send one — all I ask is that you tell me what breaks.
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