(1)x²-6x-18=0x²-6x-9-9=0(x-3)²=9x-3=3 或x-3=-3x=6 或x=0(2)x²+2(x-1)=0x²+2x-2=0(x-1)²=0 x-1=0 x=1(3)x²-2x-35=0x²-2x-1-34=0(x-1)²=34 (4)7x(5x+2)=6x(5x+2)7x(5x+2)-6x(5x+2)=0(5x+2)(7x-6x)=0x(5x+2)=0x=0