Question

(3m + n )(3m − n )solve by using foil

Answer 1

Given: The expression below

`(3m+n)(3m-n)`

To: Solve using foil

Solution

foil means

F---- FIRST

O- OUTER

I ---- INNER

L ----- LAST

Let us apply the foil method

Therefore,

`\begin{gathered} (3m+n)(3m-n) \\ =3m*3m+3m*-n+n*3m+n*-n \\ =9m^2-3mn+3mn-n^2 \\ -3mn+3mn=0 \\ Therefore \\ (3m+n)(3m-n)=9m^2-n^2 \end{gathered}`

Hence, the solution is

9m² - n²