题目化简:(1)3a2+2ab+(−3a2+2ab)(1)3a^{2}+2ab+(-3a^{2}+2ab)(1)3a2+2ab+(−3a2+2ab)；(2)(2x2+3x−12)−4(x−x2+12)(2)({2{x^2}+3x-\frac{1}{2}})-4({x-{x^2}+\frac{1}{2}})(2)(2x2+3x−21)−4(x−x2+21).知识点：整式化简求值章节：未标注
