题目计算题:(1)x(x−2)−(x+1)(x−1)(1)x\left(x-2\right)-\left(x+1\right)\left(x-1\right)(1)x(x−2)−(x+1)(x−1)；(2)(y−1+1−3yy+1)÷y2−6y+9y+1(2)(y-1+\frac{1-3y}{y+1})÷\frac{{y}^{2}-6y+9}{y+1}(2)(y−1+y+11−3y)÷y+1y2−6y+9.知识点：解二元一次方程组——代入消元法章节：方程与不等式 / 二元一次方程组
