Generic Rectangle Calculator
Use a generic rectangle to expand or factor a quadratic.
The generic rectangle (area model) helps factor a quadratic by splitting the middle term.
The math behind it
The diagonal cells of the rectangle hold ax² and c; the other diagonal must multiply to ac and add to b. The roots give the factors a(x − r₁)(x − r₂).
Worked example
x² + 7x + 10 → roots −2 and −5 → (x + 2)(x + 5).
FAQ
When can't I factor over integers?
When the discriminant b² − 4ac isn't a perfect square.