题目先化简,再求值:2(x2y+12xy2)−3(x2y−1)−2xy2−12({x}^{2}y+\frac{1}{2}x{y}^{2})-3({x}^{2}y-1)-2x{y}^{2}-12(x2y+21xy2)−3(x2y−1)−2xy2−1,其中x=−2x=-2x=−2,y=2y=2y=2.知识点：整式化简求值章节：数与式 / 整式
