化简: (1)(x+2)2-(2x)2; (2)(2a+3b)2-4a(a+3b+1).
问题描述:
化简:
(1)(x+2)2-(2x)2;
(2)(2a+3b)2-4a(a+3b+1).
答
(1)(x+2)2-(2x)2,
=x2+4x+4-4x2,
=-3x2+4x+4;
(2)(2a+3b)2-4a(a+3b+1),
=4a2+12ab+9b2-4a2-12ab-4a,
=9b2-4a.