图
x=2或x=k+1解析：x²-(k+3)x+2k+2=0x²-(k+3)x+2(k+1)=0(x-2)(x-k-1)=0x=2或x=k+1
十字相乘法1 -21 -（k+1)原式=[x-2][x-(k+1)]
(x-2)[x-(k+1)]=0(x-2)(x-k-1)=0
