题目先化简,再求值:2(a2b+12ab2)−3(a2b−1)−ab2−12(a^2b+\frac{1}{2}ab^2)-3(a^2b-1)-ab^2-12(a2b+21ab2)−3(a2b−1)−ab2−1,其a=−2a=-2a=−2,b=2b=2b=2.知识点：整式化简求值章节：数与式 / 整式
