Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

-2*x*(2*x+10)-4*(10-x^2) == 0

⇒ algebra.equations.quadratic.same-con-factor

-x*(2*x+10)-2*(10-x^2) == 0

⇒ algebra.equations.linear.distr-times

-2*x^2-10*x-20+2*x^2 == 0

⇒ algebra.equations.quadratic.same-con-factor

-x^2-5*x-10+x^2 == 0

⇒ algebra.equations.linear.merge

-5*x-10 == 0

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

-5*x == 10

⇒ algebra.equations.coverup.times

x == -2