Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

9*x^2-6 == 75

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

9*x^2 == 81

⇒ algebra.equations.coverup.times

x^2 == 9

⇒ algebra.equations.coverup.power

x == 3 or x == -3