Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

1/4*(17-x^2) == 2

⇒ algebra.equations.coverup.times

17-x^2 == 8

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

x^2 == 9

⇒ algebra.equations.coverup.power

x == 3 or x == -3