Exercise algebra.equations.quadratic.no-abc
Description
solve a quadratic equation without abc-formula
Derivation
![](http://ideas.cs.uu.nl/images/external.png)
9*x^2+30*x-15+(x-5)^2 == 0
⇒ algebra.equations.quadratic.distr-square9*x^2+30*x-15+x^2-10*x+25 == 0
⇒ algebra.equations.linear.merge10*x^2+20*x+10 == 0
⇒ algebra.equations.quadratic.scalex^2+2*x+1 == 0
⇒ algebra.equations.quadratic.nice-factors(x+1)^2 == 0
⇒ algebra.equations.coverup.powerx+1 == 0
⇒ algebra.equations.coverup.onevar.plusx == -1