化简 (a+b)²+2a(a-1/2b)-3(a-b)(a+b)
问题描述：
化简 (a+b)²+2a(a-1/2b)-3(a-b)(a+b)
答
(a+b)^2+2a(a-1/2b)-3(a-b)(a+b)
=a^2+2ab+b^2+2a^2-ab-3a^2+3b^2
=ab+4b^2
=b(a+4b)