初一数学题

显示全部楼层 · 2009-8-3 17:04:10

1.解原式=(2x-2y)(x+2y+3x+2y)-8(x-y)2
=(2x-2y)(4x+4y)-8(x-y)2
=2(4x2-4y2)-8(x-y)2
=8(x2-y2-x2-y2+2xy)
=16y(x-y)2.
(a+2b)(a+b)-(a-b)（a-2b)+(2a-b)(3a+b)解原式 =a2+3ab+2b2 - a2+3ab-2b2 + 6a2-ab-b2
=6a2+5ab...

千问 · 2009-8-3 17:04:10

1.（x+2y）（2x-2y）+（2x-2y）（3x+2y）-8（x-y）2=2x2+2xy-4y2 + 6x2-2xy-4y2 - 8x2+16xy-8y2=16xy-16y2=16y(x-y)2.(a+2b)(a+b)-(a-b)（a-2b)+(2a-b)...

千问 · 2009-8-3 17:04:10

原式=8(x+y)(x-y)-8(x-y)(x-y)=16y(x-y)原式=(a+2b)(a+b)-(a+b)(a-2b)+2b(a-2b)+(2a-b)(3a+b)
=4b(a+b)+2b(a-2b)+(2a-b)(3a+b)
=2b(3a+b)+(2a-b)(3a+b)
=(2a+b)(3a+b)...

千问 · 2009-8-3 17:04:10

（x+2y）（2x-2y）+（2x-2y）（3x+2y）-8（x-y）2=(2x-2y) (x+2y+3x+2y)-8(x-y)2=`(2x-2y)(4x-4y)-8(x-y)2=8(x-y)(x+y-x+y)=16y(x-y)2.(a+2b)(a+b)-(a-b（a-2b)+(2a-b)(3a+...

千问 · 2009-8-3 17:04:10

1、=2(x+2y)(x-y)+2(x-y)(3x+2y)-8(x-y)2 =2(x-y)(x+2y+3x+2y)-8(x-y)2 =2(x-y)(4x+4y)-8(x-y)2 =8(x-y)(x+y)-8(x-y)(x-y) =8(x-y)(x+y-x+y) =16y(x-y) ...