Exercise algebra.equations.quadratic.no-abc
Description
solve a quadratic equation without abc-formula
Derivation
40-4*x^2 == -4*x^2-20*x
⇒ algebra.equations.quadratic.cancel40 == -20*x
⇒ algebra.equations.coverup.times-2 == x
⇒ algebra.equations.linear.flipx == -2