(x+3)²-3(x+3)+2=0(x+3-1)(x+3-2)=0(x+2)(x+1)=0X=-2,x=-1
用换元法设m=x+3原方程变为：m^2-3m+2=0(m-1)(m-2)=0m=1或m=2x+3=1,x=-2x+3=2，x=-1
