Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

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

⇒ algebra.equations.quadratic.prepare-split

x^2+4*x+4 == 8

⇒ algebra.equations.quadratic.left-square

(x+2)^2 == 8

⇒ algebra.equations.coverup.power

x+2 == sqrt 8 or x+2 == -sqrt 8

⇒ algebra.equations.coverup.onevar.plus

x == -2+sqrt 8 or x+2 == -sqrt 8

⇒ algebra.equations.coverup.onevar.plus

x == -2+sqrt 8 or x == -2-sqrt 8

⇒ algebra.equations.quadratic.simpler-sqrt

x == -2+2*sqrt 2 or x == -2-2*sqrt 2