[latex]I sposob\ frac{1}{f}=frac{1}{x}+frac{1}{y}\ Wyrazenie po prawej sprowadzamy do wspolnego mianownika:\ frac{1}{f}=frac{y}{xy}+frac{x}{xy}\ frac{1}{f}=frac{y+x}{xy}\ f=frac{xy}{y+x}|*(x+y)\ f(x+y)=frac{xy}{x+y}(x+y)\ fx+fy=xy\ Wyrazenia z "y" na lewa strone:\ fy-xy=-fx\ xy-fy=fx\ Wylaczasz "y" przed nawias:\ y(x-f)=fx|*frac{1}{x-f}\ y(x-f)*frac{1}{x-f}=fx*frac{1}{x-f}\ oxed{underline{y=frac{fx}{x-f}}}[/latex] [latex]II sposob:\ frac{1}{f}=frac{1}{x}+frac{1}{y}|*fxy\ xy=fy+fx\ xy-fy=fx\ y(x-f)=fx\ oxed{underline{y=frac{fx}{x-f}}}[/latex] [latex]III sposob:\ frac{1}{f}=frac{1}{x}+frac{1}{y}\ frac{1}{f}-frac{1}{x}=frac{1}{y}\ frac{x-f}{fx}=frac{1}{y}\ frac{fx}{x-f}=y\ oxed{underline{y=frac{fx}{x-f}}}[/latex]
