Brevity is a gift

Explanation From Original OP:

The Abel-Ruffini theorem says that general polynomial equations of degree 5 or higher do not have an algebraic solution when using arbitrary coefficients.

Ruffini’s 1799 proof is known to contain some errors, and met little interest at the time. The first complete proof was delivered by Niels Abel 25 years later; it only took him 6 pages.