几道数学题·初二从第三题往下一定要写过程，快没分了%>_<%

显示全部楼层 · 2010-9-25 13:43:50

1.（mn-1)2 -(mn-1)(mn+1)2.(x+y/2)2 +(x-y/2)2 3. a^4-(a-b)(a+b)(a2 -b2 )
5.(x-1)2 +(y+2)2 -(x+y)(x-y)6.97×99×101×103=？（用乘法公式）
还剩5分！！！！！！

千问 · 2010-9-25 13:43:50

解：1.（mn-1)2 -(mn-1)(mn+1)
=（mn-1)（mn-1-mn-1)
=1-mn 2.(x+y/2)2 +(x-y/2)2
=(x+y/2)2+(x-y/2)(x+y/2)
=(x+y/2)(x+y/2+x-y/2)
=(x+y/2)2x
=2x2+xy
=x(2x+y)
3. a^4-(a-b)(a+b)(a2 -b2 )
=a^4-(a2 -b2 ))(a2 -b2 )
=a^4- [(

千问 · 2010-9-25 13:43:50

-m2n2-2mn+3
2x2+2xy+y2/2 a^4-(a-b)(a+b)(a2 -b2 )= a^4-(a2-b2)2=2a2b2-b^4(x-1)2 +(y+2)2 -(x+y)(x-y) =4y-

千问 · 2010-9-25 13:43:50

1.（mn-1)2 -(mn-1)(mn+1)＝(mn-1)[mn-1-(mn+1)]＝-2(mn-1)2.(x+y/2)2 +(x-y/2)2＝2x2 +y2 /23. a^4-(a-b)(a+b)(a2 -b2)＝a^4 -(a2 -b&sup

几道数学题·初二 从第三题往下一定要写过程，快没分了%>_<%

几道数学题·初二从第三题往下一定要写过程，快没分了%>_<%