2x(x-3)-(x-3)(x+6)=x^2+12（x-3)(2x--x-6)=x^2+12 (x-3)(x-6)=x^2+12x^2-9x+18=x^2+12 -9x+6=0x=-2/3
2x^2-6x-(x^2+3x-18)=x^2+122x^2-6x-x^2-3x+18=x^2+122x^2-2x^2-6x-3x+18-12=0-9x+6=0-9x=-6x=2/3
2/3
