Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

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

⇒ algebra.equations.quadratic.left-square

(x+3)^2 == 9

⇒ algebra.equations.coverup.power

x+3 == 3 or x+3 == -3

⇒ algebra.equations.coverup.onevar.plus

x == 0 or x+3 == -3

⇒ algebra.equations.coverup.onevar.plus

x == 0 or x == -6