Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

12*(x^2-3*x)+8 == 56

⇒ algebra.equations.coverup.onevar.plus

12*(x^2-3*x) == 48

⇒ algebra.equations.coverup.times

x^2-3*x == 4

⇒ algebra.equations.quadratic.move-left

x^2-3*x-4 == 0

⇒ algebra.equations.quadratic.nice-factors

(x+1)*(x-4) == 0

⇒ algebra.equations.quadratic.product-zero

x == -1 or x == 4