Question

计算或化简 (3m-n)(-3m-n)-(m-2n)^2-(m-2n)(2m-n)

求大师

Answer 1

你好，我也没有用简便方法，是直接算出来的，希望能采纳。
如下：
(3m-n)(-3m-n)-(m-2n)^2-(m-2n)(2m-n)

=-9m^2+3mn-3mn+n^2-m^2+4mn-4n^2-2m^2+4mn+mn-2n^2
=-12m^2-5n^2+9mn

希望能够帮到你！

Answer 2

原式=(n-3m)(n+3m)-(m-2n)[(m-2n)-(2m-n)]
=(n-3m)(n+3m)+(m-2n)(m+n)
=(n²-9m²)+(m²-mn-2n²)
= -n²-mn-8m²

Answer 3

　　(3m-n)(-3m-n)-(m-2n)^2-(m-2n)(2m-n)

= -（9m^2-n^2）-(m^2-4mn+4n^2)-(2m^2-4mn-mn+2n^2)
= - 9m^2+n^2-m^2+4mn-4n^2-2m^2+5mn-2n^2
= - 12m^2-5n^2+9mn