Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

-x*(x+2)+2*x^2-7 == 0

⇒ algebra.equations.linear.distr-times

-x^2-2*x+2*x^2-7 == 0

⇒ algebra.equations.linear.merge

x^2-2*x-7 == 0

⇒ algebra.equations.quadratic.prepare-split

x^2-2*x+1 == 8

⇒ algebra.equations.quadratic.left-square

(x-1)^2 == 8

⇒ algebra.equations.coverup.power

x-1 == sqrt 8 or x-1 == -sqrt 8

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

x == 1+sqrt 8 or x-1 == -sqrt 8

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

x == 1+sqrt 8 or x == 1-sqrt 8

⇒ algebra.equations.quadratic.simpler-sqrt

x == 1+2*sqrt 2 or x == 1-2*sqrt 2