C=√7/LA
C=√7/LA, solve for L
C=√7/LA square both sides C^2=7/LA cross multiply C^2LA = 7 L=7 / [C^2A]
\(C=\frac{\sqrt7}{LA}\\ CA=\frac{\sqrt7}{L}\\ \frac{1}{CA}= \frac{L}{\sqrt7}\)
I will not give the last step to you. Think of it yourself. (Tips: How to make the right hand side remain only a 'L'?)