Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

2*(x^2-3) == 12

⇒ algebra.equations.coverup.times

x^2-3 == 6

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

x^2 == 9

⇒ algebra.equations.coverup.power

x == 3 or x == -3