The tension in a string is $13\mathrm{.}6$N$,$ and its linear density is $0\mathrm{.}752$ kg$/$m$.$ A wave on the string travels toward the $-$x direction; it has an amplitude of $4\mathrm{.}18$ cm and a frequency of $13\mathrm{.}7$ Hz$.$ What are the speed and wavelength of the wave? Write down a mathematical expression for the wave, substituting numbers for the variables A$,$ f$,$ and