9X2+6X+1=(3x+1)^2所以(3x+1)^2=43x+1=2或3x+1=-2x1=1/3 x2=-1
9x^2+6x-3=0(9x-3)(x+1)=0x=1/3 x=-1
9x*x+6x+1=49x*x+6x-3=03x*x+2x-1=0(3x-1)(x+1)=0x1=1/3 x2=-1
