The wavelenght of the harmonics in a string of a guitar is given as:
[tex]\lambda=\frac{2}{n_i}L[/tex]where L is the lenght of the guitar string and ni is the harmonic we like tu calculate, using this formula we have the first 5 harmonics.
[tex]\begin{gathered} \lambda_1=\frac{2}{1}(0.75)=1.5 \\ \lambda_2=\frac{2}{2}(0.75)=0.75 \\ \lambda_3=\frac{2}{3}(0.75)=0.5 \\ \lambda_4=\frac{2}{4}(0.75)=0.375 \\ \lambda_5=\frac{2}{5}(0.75)=0.3 \end{gathered}[/tex]