(a+b)平方+(a+c)平方-(c+d)&平方-(b+d)平方

显示全部楼层 · 2011-3-12 19:14:38

(a+b)平方+(a+c)平方-(c+d)平方-(b+d)平方 =[(a+b+b+d)(a+b-b-d)]+[(a+c+c+d)(a+c-c-d)]=[(a+2b+d)(a-d)]+[(a+2c+d)(a-d)]=(a-d)[(a+2b+d)+(a+2c+d)]=(a-b)(2a+2b+2c+2d)=2(a-b)(a+b+c+d)...

千问 · 2011-3-12 19:14:38

解答：(a+b)^2+(a+c)^2-(c+d)^2-(b+d)^2=a^2+2ab+b^2+a^2+2ac+c^2-c^2-2cd-d^2-b^2-2bd-d^2=2a^2+2ab+2ac-2cd-2bd-2d^2...

千问 · 2011-3-12 19:14:38

2（a*(a+b+c)-d*(b+c+d))...