问题
解答题
算一算!千万别出错!
(1)-t(-t)2-t3;
(2)(-2a)3-(-a)-(3a)2;
(3)(3xy2)2+(-xy)-(-4xy3);
(4)(x-1)(x2+x+1);
(5)(2x+y)(2x-y)-(2x-y)2;
(6)(a-2b+c)(a+2b+c).
答案
(1)原式=-t3-t3=-2t3;
(2)原式=-8a3-(-9a3)=a3;
(3)原式=9x2y4+4x2y4=13x2y4;
(4)由立方差公式知:(x-1)(x2+x+1)=x3-1;
(5)原式=4x2-y2-(4x2-4xy+y2)=4xy-2y2;
(6)原式=(a+c)2-4b2=a2+2ac+c2-4b2.