So... I know the answer to the question because it's something we worked on in class... but there's one part I don't get.

Question

Factoring

m - 2n + m^2 - 4n^2

m - 2n + (m + 2n) (m - 2n)

Then there's a 1...

1(m - 2n) (m + 2n) (m - 2n)

AND my question is...
How and why does this 1 go over here and do this from the step above?? ...

(m - 2n) (1 + m + 2n)

And the answer somehow is

(m - 2n) (1 + m + 2n)

m - 2n + (m + 2n) (m - 2n)
(m - 2n) + (m + 2n) (m - 2n)
This is like
a + b a
a(1+b) where a is m-2n and b is m+2n

Answer 1

good