the Answer:
The expression is given below as
[tex](m+\frac{8}{9}n)(m-\frac{8}{9}n)[/tex]Concept:
The multiplication of conjugates by using product of conjugates pattern is given below as
[tex]\begin{gathered} (a-b)(a+b) \\ =a(a+b)-b(a+b) \\ =a^2+ab-ab-b^2 \\ (a-b)(a+b)=a^2-b^2 \end{gathered}[/tex]By comparing coefficient, we will have
[tex]a=m,b=\frac{8}{9}n[/tex][tex]\begin{gathered} (m+\frac{8}{9}n)(m-\frac{8}{9}n)=m^2-(\frac{8}{9}n)^2 \\ (m+\frac{8}{9}n)(m-\frac{8}{9}n)=m^2-\frac{64}{81}n^2 \end{gathered}[/tex]Hence,
The final answer is given below as
[tex]m^2-\frac{64}{81}n^2[/tex]