Question Number 132747 by aurpeyz last updated on 16/Feb/21
Commented by mr W last updated on 16/Feb/21
$$\frac{\mathrm{1}}{{s}}+\frac{\mathrm{1}}{{s}'}=\frac{\mathrm{2}}{{R}} \\ $$$$\frac{\mathrm{1}}{{s}}+\frac{\mathrm{1}}{−\mathrm{2}}=\frac{\mathrm{2}}{−\mathrm{12}} \\ $$$$\frac{\mathrm{1}}{{s}}=\frac{\mathrm{1}}{\mathrm{3}} \\ $$$$\Rightarrow{s}=\mathrm{3} \\ $$
Commented by aurpeyz last updated on 17/Feb/21
$${thank}\:{you}\:{Sir} \\ $$
Commented by aurpeyz last updated on 17/Feb/21
$${according}\:{to}\:{this}\:{sign}\:{convention} \\ $$$${will}\:{an}\:{upright}\:{imahe}\:{be}\:{positive} \\ $$$${or}\:{negative}? \\ $$
Commented by mr W last updated on 17/Feb/21
$${the}\:{forum}\:{here}\:{is}\:{never}\:{a}\:{good}\:{place} \\ $$$${to}\:{learn}\:{basic}\:{things}... \\ $$
Commented by aurpeyz last updated on 17/Feb/21
$${is}\:{there}\:{anyway}\:{you}\:{can}\:{help}\:{me}? \\ $$
Answered by Dwaipayan Shikari last updated on 16/Feb/21
$$\frac{\mathrm{1}}{{x}_{{o}} }+\frac{\mathrm{1}}{{x}_{{i}} }=\frac{\mathrm{1}}{{f}}\:\:\:\:\:\:\:\:\:\:\:{f}=\frac{{R}}{\mathrm{2}} \\ $$$$\frac{\mathrm{1}}{{x}_{{o}} \:}=\frac{\mathrm{1}}{{f}}−\frac{\mathrm{1}}{{x}_{{i}} }\:\:\:\:\:\:\:\:\:\:\:{x}_{{i}} =−\mathrm{2}\:\:\:\:{f}=−\mathrm{6} \\ $$$${x}_{{o}} =+\mathrm{3}\:\:{cm}\: \\ $$
Commented by aurpeyz last updated on 17/Feb/21
$${thank}\:{you}\:{Sir} \\ $$