Exercise algebra.equations.quadratic.no-abc
Description
solve a quadratic equation without abc-formula
Derivation
![](http://ideas.cs.uu.nl/images/external.png)
-x^2-12*x-20 == 0
⇒ algebra.equations.quadratic.nice-factors(x+2)*(x+10) == 0
⇒ algebra.equations.quadratic.product-zerox == -2 or x == -10