Question 108507
(m^2-5mn + 3n^2)(m^2+4mn - 2n^2)
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{{{(m^2)(m^2+4mn-2n^2)-(5mn)(m^2+4mn-2n^2)+(3n^2)(m^2+4mn-2n^2)}}}
{{{m^4+4m^3n-2m^2n^2-5m^3n-20m^2n^2+10mn^3+3m^2n^2+12mn^3-6n^4}}}
Now collect like terms;
{{{m^4+4m^3n-5m^3n-2m^2n^2-20m^2n^2+3m^2n^2+10mn^3+12mn^3-6n^4}}}
{{{m^4-m^3n-19m^2n^2+22mn^3-6n^4}}}
:)