初一综合运用整式及其加减约 18 分钟化简：（1）3x2−6x−x2−3+4x−2x2−13x^2-6x-x^2-3+4x-2x^2-13x2−6x−x2−3+4x−2x2−1；（2）(x2y+xy)+3(x2y−xy)−4x2y(x^2y+xy)+3(x^2y-xy)-4x^2y(x2y+xy)+3(x2y−xy)−4x2y。完整作答把思路留在纸面上01条件转化02关键计算03完整结论
