Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

x^2-6*x == 4

⇒ algebra.equations.quadratic.move-left

x^2-6*x-4 == 0

⇒ algebra.equations.quadratic.prepare-split

x^2-6*x+9 == 13

⇒ algebra.equations.quadratic.left-square

(x-3)^2 == 13

⇒ algebra.equations.coverup.power

x-3 == sqrt 13 or x-3 == -sqrt 13

⇒ algebra.equations.coverup.onevar.minus-left

x == 3+sqrt 13 or x-3 == -sqrt 13

⇒ algebra.equations.coverup.onevar.minus-left

x == 3+sqrt 13 or x == 3-sqrt 13