Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

(6-2*x)^2 == 81

⇒ algebra.equations.coverup.power

6-2*x == 9 or 6-2*x == -9

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

2*x == -3 or 6-2*x == -9

⇒ algebra.equations.coverup.times

x == -3/2 or 6-2*x == -9

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

x == -3/2 or 2*x == 15

⇒ algebra.equations.coverup.times

x == -3/2 or x == 15/2