Exercise algebra.inequalities.quadratic

Description
solve a quadratic inequation

Derivation

-x^2+3*x+18 == 0

⇒ algebra.equations.quadratic.simpler-poly

x^2-3*x-18 == 0

⇒ algebra.equations.quadratic.nice-factors

(x+3)*(x-6) == 0

⇒ algebra.equations.quadratic.product-zero

x == -3 or x == 6