Question

How do you factor `mn^4 - 5m^2n^3 - 4m^3n^2 + 20 m^4n`?

Answer 1

`(mn^3-4m^3n)(n-5m)`

Explanation:

`mn^4-5m^2n^3-4m^3n^2+20m^4n`

= `(mn^4-5m^2n^3)-(4m^3n^2-20m^4n)`

= `(mn^3)(n-5m)-4m^3n(n-5m)`

= `(mn^3-4m^3n)(n-5m)`