计算: (1) x2(x-1)-(x+1)(x2+x); (2) (2x+1)2-(x+3)(x-3)-(x-1)2 答案:解:原式= x3−x2−(x3+x2+x2+x) = x3−x2−x3−x2−x2−x = −3x2−x ;
解:原式= 4x2+4x+1−x2+9−x2+2x−1 = 2x2+6x +9.
Wait for a few
minutes, your watch____ now.
A. will be
repaired B. has been repaired C. is
being repaired D. has repaired