计算：(x+3)(x-1)-x(x-4)要过程(2m-3n)(n+4n)-(m+n)(2m+5n)
问题描述：
计算：(x+3)(x-1)-x(x-4)要过程(2m-3n)(n+4n)-(m+n)(2m+5n)
答
(x+3)(x-1)-x(x-4)=x²-x+3x-3-x²+4x=6x-3(2m-3n)(n+4n)-(m+n)(2m+5n)=(2m-3n)×5n-(m+n)(2m+5n)=10mn-15n²-2m²+5mn+2nm+5n²=17mn-2m²-10n²`(*∩_∩*)′