x2+x=5x+6x2 -5x - 6 = 0 (x-6) (x+1 ) = 0 x = 6 或者 x=-1x²+x=5x+6x2 -4x -6 = 0x= 4±根号(16+24) / 2= 2±根号107x²-5=x+8 7x2-x -13 = 0 x = 1±根号(1+ 364)/ 14= ( 1±根号365 )/ 14