Question 112695
(m^2-5mn+3n^2)(m^2+4mn-2n^2)

First multiply m^2 by the polynomial on the right:
m^4+4m^3n-2m^2n^2

Next multiply -5mn by the ploynomial on the right:
-5m^3n-20m^2n^2+10mn^3

Next multiply 3n^3 by the polynomial on the right:
3m^2n^2+12mn^3-6n^4

Now simplify:
m^4+4m^3n-2m^2n^2
   -5m^3n-20m^2n^2+10mn^3 
         +3m^2n^2+12mn^3-6n^4

= m^4-m^3n-15m^2n^2+22mn^3-64n^4