Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

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

⇒ algebra.equations.linear.distr-times

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

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

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

⇒ algebra.equations.linear.flip

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

⇒ algebra.equations.linear.merge

10+5*x == 0

⇒ algebra.equations.coverup.onevar.plus

5*x == -10

⇒ algebra.equations.coverup.times

x == -2