题目(1)(1)(1)化简:(3a−4a2+1)−(5a2−a)(3a-4a^{2}+1)-(5a^{2}-a)(3a−4a2+1)−(5a2−a)；(2)(2)(2)先化简,再求值:3x2y−2(x2y+xy2)3x^{2}y-2(x^{2}y+xy^{2})3x2y−2(x2y+xy2),其中x=−1x=-1x=−1,y=2y=2y=2.知识点：整式化简求值章节：数与式 / 整式
