Exercise algebra.equations.quadratic.no-abc
Description
solve a quadratic equation without abc-formula
Derivation
![](http://ideas.cs.uu.nl/images/external.png)
6-2*x == 9 or 6-2*x == -9
⇒ algebra.equations.coverup.onevar.minus-right2*x == -3 or 6-2*x == -9
⇒ algebra.equations.coverup.timesx == -3/2 or 6-2*x == -9
⇒ algebra.equations.coverup.onevar.minus-rightx == -3/2 or 2*x == 15
⇒ algebra.equations.coverup.timesx == -3/2 or x == 15/2