Harison ,
[tex3]\text{I}=\frac{2}{3}.\log\left(\frac{\text{E}}{7.10^{-3}}\right)[/tex3]
[tex3]\text{I}=\frac{2}{3}.[\log\text{E} -\log({7.10^{-3}})][/tex3]
[tex3]\text{I}=\frac{2}{3}.[\log\text{E} -(\log{7+\log10^{-3}})][/tex3]
[tex3]\text{I}=\frac{2}{3}.[\log\text{E} -\log7+3][/tex3]
Para [tex3]\text{I}=8[/tex3]
[tex3]8=\frac{2}{3}.[\log\text{E} -\log7+3][/tex3]
[tex3]\log\left(\frac{\text{E}}{7}\right)=9[/tex3]
[tex3]{\color{red}\boxed{\text{E}=7.10^9 \text{ kwh}}}[/tex3]
b)
[tex3]\text{I}=\frac{2}{3}.[\log\text{E} -\log7+3][/tex3]
[tex3]9=\frac{2}{3}.[\log\text{E'} -\log7+3][/tex3]
[tex3]\log\left(\frac{\text{E'}}{7}\right)=10,5[/tex3]
[tex3]\text{E'}=7.10^{10,5}[/tex3]
[tex3]\text{E'}=\text{k}.\text{E}[/tex3]
[tex3]7.10^{10,5}=\text{k}.7.10^{9}[/tex3]
[tex3]\text{k}=10^{10,5-9}=10^{1,5}[/tex3]
[tex3]\text{k}=10^1.10^{0,5}[/tex3]
[tex3]{\color{red}\boxed{\text{k}≈31,6}}[/tex3]