Solution:
Given:
[tex]\begin{gathered} a\text{\textasciitilde b}=\frac{\left(ab\right)}{\left(a-b\right)} \\ \end{gathered}[/tex][tex]\begin{gathered} \lparen2\text{\textasciitilde3\rparen\textasciitilde4} \\ \lparen2\text{\textasciitilde3\rparen}=\frac{\left(2\times3\right)}{\left(2-3\right)}=\frac{6}{-1}=-6 \end{gathered}[/tex]
Hence, solving further,
[tex]\begin{gathered} \lparen2\text{\textasciitilde3\rparen\textasciitilde4}=\left(-6\text{\textasciitilde4}\right? \\ \lparen-6\text{\textasciitilde4\rparen}=\frac{\left(-6\times4\right)}{\left(-6-4\right)}=\frac{-24}{-10} \\ \lparen2\text{\textasciitilde3\rparen\textasciitilde4}=2.4 \end{gathered}[/tex]
Therefore, the value of (2~3)~4 is 2.4
