(m+4n)(m-n)-6(m+2n)(m-3n),

问题描述:

(m+4n)(m-n)-6(m+2n)(m-3n),

=(m²+3mn-4n²)-6(m²-mn-6n²)
=m²+3mn-4n²-6m²+6mn+36n²
= -5m²-9mn+32n²