Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

-(x-2)*(x+6)+4*x == 0

⇒ algebra.equations.linear.distr-times

-x^2-4*x+12+4*x == 0

⇒ algebra.equations.linear.merge

-x^2+12 == 0

⇒ algebra.equations.quadratic.no-lin

x^2 == 12

⇒ algebra.equations.coverup.power

x == sqrt 12 or x == -sqrt 12

⇒ algebra.equations.quadratic.simpler-sqrt

x == 2*sqrt 3 or x == -2*sqrt 3