概華论与款醒统外 由F(x)=nfx)dx得 0,x<0, dx 0sx<3 6 F(x)= 心ax+2-iux,3≤x<4 1,x≥4.           + −      =    1, 4. )d , 3 4, 2 d (2 6 d , 0 3, 6 0, 0, ( ) 3 0 3 0 x x x x x x x x x x F x x x 由  得 − = x F(x) f (x)d x