题目(1)(−12)−2+∣π−3∣+(−5)0+(−1)2022(1)(-\frac{1}{2})^{-2}+|\pi -3|+\left(-5\right)^{0}+\left(-1\right)^{2022}(1)(−21)−2+∣π−3∣+(−5)0+(−1)2022；(2)(2)(2)先化简,再求值(x+y+z)(x+y−z)−12[(x+y)2−(x−y)2]\left(x+y+z\right)\left(x+y-z\right)-\frac{1}{2}[\left(x+y\right)^{2}-\left(x-y\right)^{2}](x+y+z)(x+y−z)−21[(x+y)2−(x−y)2],其中x=1x=1x=1,y=2y=2y=2,z=3z=3z=3.知识点：单项式乘多项式章节：数与式 / 整式
