x²-8x+12=0(x-6)(x-2)=0x=6或x=2x²-6x=7x²-6x-7=0（x-7）（x+1）=0x=7 或x=-1x²-2x=7(x-1)²-1=7(x-1)²=8x-1=±2√2x=1+2√2或x=1-2√2x²-x=2x²-x-2=0(x+1)(x-2)=0x=-1或x=2...