Question

初二简单的计算题,大家一起来做一做啊

Answer 1

(2a+b)^2-4a(a+b)=4a^2+4ab+b^2-4a^2-4ab=b^2

(a+b)^2-(a-b)^2=(a+b+a-b)(a+b-a+b)=2a*2b=4ab

(a+b-c-d)(a-b+c-d)=[(a-d)+(b-c)][(a-d)-(b-c)]

=(a-d)^2-(b-c)^2=a^2-2ad+d^2-b^2+2bc-c^2