[tex]\left\{\begin{array}{l}U=R*I\\I=\frac{E}{R+r} \end{array}\right =>\left\{\begin{array}{l}I=\frac{U}{R} \\I=\frac{E}{R+r} \end{array}\right\\\frac{U}{R}= \frac{E}{R+r}<=>U(R+r)=RE<=>UR+Ur=RE<=>R(U-E)=-Ur=>R=\frac{-Ur}{U-E}=\frac{-9,6*2}{9,6-12}=\frac{19,2}{2,4}=8 \Omega\\ R=8\Omega\\I_{sc}=\frac{E}{r}=\frac{12}{2}=6 A\\ I_{sc}=6 A[/tex]
