求比多项式7m²-4mn-n²少2m²-mn+2n²的多项式,

问题描述:

求比多项式7m²-4mn-n²少2m²-mn+2n²的多项式,

(7m²-4mn-n²)-(2m²-mn+2n²)=5m²-3mn-3n²