$$V=5.5\sqrt{0.6l+\frac{P}{100}}$$
$P=\frac{400V^{2}}{121}-60l$
$V\geq 0$
$P=\frac{400V^{2}}{121}-60l$
$arg(V)<\pi \text{ or }V=0$
$V=\frac{11\sqrt{P+60l}}{20}$
$V=\frac{11\sqrt{P+60l}}{20}$
$l\geq -\frac{P}{60}$