( x + 1 )" - ( 2x - 3 )" = 0
( 2x - 3 )" - ( x + 1 )" = 0
( 2x - 3 - x - 1 )( 2x - 3 + x + 1 ) = 0
( x - 4 )( 3x - 2 ) = 0
解方程得
x1 = 4 ,
x2 = 2/3