[Risolto] proporzione con i medi uguali

$\big[\big(\frac{1}{4} : \frac{5}{4} +1\big)^2 : \frac{9}{5}\big] : x = x : \big[\big(\frac{5}{2}-\frac{1}{3}-\frac{7}{4}\big)·\frac{9}{5}\big]$

$\big[\big(\frac{1}{4}·\frac{4}{5} +1\big)^2·\frac{5}{9}\big] : x = x : \big[\big(\frac{30-4-21}{12}\big)·\frac{9}{5}\big]$

$\big[\big(\frac{1}{1}·\frac{1}{5} +1\big)^2·\frac{5}{9}\big] : x = x : \big[\frac{5}{12}·\frac{9}{5}\big]$

$\big[\big(\frac{1}{5} +1\big)^2·\frac{5}{9}\big] : x = x : \big[\frac{1}{4}·\frac{3}{1}\big]$

$\big[\big(\frac{1+5}{5}\big)^2·\frac{5}{9}\big] : x = x : \frac{3}{4}$

$\big[\big(\frac{6}{5}\big)^2·\frac{5}{9}\big] : x = x : \frac{3}{4}$

$\big[\frac{36}{25}·\frac{5}{9}\big] : x = x : \frac{3}{4}$

$\big[\frac{4}{5}·\frac{1}{1}\big] : x = x : \frac{3}{4}$

$\frac{4}{5} : x = x : \frac{3}{4}$

$x^2 = \frac{3}{4}·\frac{4}{5}$

$x^2 = \frac{3}{1}·\frac{1}{5}$

$x^2 = \frac{3}{5}$

$\sqrt{x^2} = \sqrt{\frac{3}{5}}$

$x= ±\frac{\sqrt{15}}{5} $ → $~(≅ ±0,774597)$.