Given: The expression below
[tex](3m+n)(3m-n)[/tex]
To: Solve using foil
Solution
foil means
F---- FIRST
O- OUTER
I ---- INNER
L ----- LAST
Let us apply the foil method
Therefore,
[tex]\begin{gathered} (3m+n)(3m-n) \\ =3m\times3m+3m\times-n+n\times3m+n\times-n \\ =9m^2-3mn+3mn-n^2 \\ -3mn+3mn=0 \\ Therefore \\ (3m+n)(3m-n)=9m^2-n^2 \end{gathered}[/tex]
Hence, the solution is
9m² - n²
