降幂配方：原式=x^2(x-6)+3x(x-6)+3(x-6)=0(x^2+3x+3)(x-6)=0则：x^2+3x+3=0无解；x-6=0有解x=6麻烦一点：画图3x^2+15x+18=x^3在坐标轴上画出y=x^3和y=3x^2+15x+18的图像，两图像的交点即为原方程的解，解为x=6
