The line should be
"the frequency of motion is ( α n ) / ( 2 L ) = ( n τ ) / ( 2 L ρ ) {\displaystyle (\alpha n)/(2L)=\left(n{\sqrt {\tau }}\right)/\left(2L{\sqrt {\rho }}\right)} Hz, where τ {\displaystyle \tau } is the tension in"
Return to errata.