Generator

algebra-tiles

A generator in the algebra library, called 8 times across 1 essays. Below: what it draws at its defaults and at each mode an essay asks for, what it checks while drawing, and everywhere it is used.

algebra-tiles is one function. Everything below came out of it during this build, at parameters taken from the essays rather than invented for this page — so a figure here is the same figure a reader meets in an essay, and if the generator changes, this page changes with it.

At its defaults

Completing the square, as a squareAn x by x square with the strip split in half and laid along two sides, leaving a square hole of side 1.5. Filling the hole costs 2.25 and buys a perfect square.1.5x1.5x1.5²x + 1.5a squarex² + 3x + 1.5²= (x + 1.5)²x = 4, so the total is30.25

show: "solve"

The same picture, solvedThe equation x² + 6x = 16 drawn as an L-shaped region of area 16. Completing it to a square of area 25 gives a side of 5.000, so x is 2.000.3x3x95.000x² + bx = kx² + 6x = 16add (b/2)² to both sidesx² + 6x + 9 = 25the left side is now a square(x + 3)² = 25so the side is its rootx + 3 = 5.0000and the length isx = 2.0000

show: "identity"

(a + b)², as four tilesA square of side 7 cut into an 5 by 5 square, a 2 by 2 square and two 5 by 2 rectangles — which is why the middle term is doubled.abab(a + b)² = a² + 2ab + b²7² = 25 + 20 + 4 = 49

What it checks while it draws

Collected by running the family and listening to lib/verify.js, not written here. The count is how many separate times this build put that claim to the test.

Where it is called

Changing this generator changes every figure on this list. That is what makes the list worth publishing rather than keeping in a check script.

The whole library · What the figures prove