XYZ-XY-XZ+X-YZ+Y+Z-1XYZ,XY提取公因式XY； XZ,X提取公因式X；YZ,Y提取公因式Y=XY(Z-1)-X(Z-1)-Y(Z-1)+(Z-1) 提取公因式(Z-1)；=(Z-1)(XY-X-Y+1)XY,X 提取公因式X =(Z-1)[X(Y-1)-(Y-1)]提取公...