已知m+2n=3,m-2n=1,则代数式16m²n²-(m²+4n²)²的值为()
问题描述:
已知m+2n=3,m-2n=1,则代数式16m²n²-(m²+4n²)²的值为()
不能先把m和n求出来,要用整体思想
答
16m²n²-(m²+4n²)²
=(4mn+m²+4n²)(4mn-m²-4n²)
=-(m+2n)²(m-2n)²
=-9×1
=-9哎呀= =我怎么没想到谢谢