Ответ:

-28.8

Объяснение:

[tex]\frac{4ac^2}{a^2-c^2}*\frac{a+c}{ac} =\frac{4ac^2*(a+c)}{(a-c)(a+c)*ac}=\frac{4c}{a-c}=\frac{4*3.6}{3.1-3.6}=\frac{14.4}{-0.5}=-28.8[/tex]

[tex]\displaystyle\bf\\\frac{4ac^{2} }{a^{2} -c^{2} }\cdot\frac{a+c}{ac} =\frac{4ac^{2} \cdot(a+c)}{(a+c)(a-c)\cdot ac} =\frac{4c}{a-c} \\\\\\a=3,1 \ \ \ ; \ \ \ c=3,6\\\\\\\frac{4c}{a-c} =\frac{4\cdot 3,6}{3,1-3,6} =\frac{14,4}{-0,5} =-28,8[/tex]