2x" - 4x + 5= 2x" - 4x + 2 + 3= 2[ ( x - 1 )" + 3/2 ]= 2[ ( x - 1 )" - ( -6/4 ) ]= 2{ ( x - 1 )" - [ (√6/ 2)i ]" }= 2[ x - 1 - (√6/ 2)i ][ x - 1 + (√6/ 2)i ]或者= 2[ 2x /2 - 2/2 - (√6/ 2)i ][ 2x /...