Question

Historical Feature:
In the equation x^3+px+q=o, replace x by H+K. Let 3HK=-p, and show that H^3+K^3=-q

Answer 1

this is how you solve the cubic equation

Answer 2

In the equation

$$
\Large{ x^3+px+q=0
\\ x= h+k
\\ 3hk=-p
\\~\\ \textrm{Goal: Show that} ~h^3+k^3=-q

}
$$