解(x-3)^2+4x(x-3)=0(x-3)[(x-3)+4x]=0(x-3)(5x-3)=0∴x=3或x=3/5(x-3)^2+4x(x-3)=0x^2-6x+9+4x^2-12x=05x^2-18x+9=0△=b^2-4ac=18^2-4×5×9=144∴x=(18+√144)/10=(18+12)/10=3或x=(18-12)/10=3/5