v()/2x1-12 Vf() 设 d'Vc1(x)≥0d1-2d2≥0 dvc2(x)≥0-31-2a2≥0 dVf(x)<0-81+2d2<0( ) ( )        −  =         − −  = 2 8 2 4 2 12 2 1 f x x x f x 设 ( ) T d d1 d2 = , d c1 (x)  0 T d1 − 2d2  0 d c2 (x)  0 T −3d1 − 2d2  0 d f (x)  0 T −8d1 + 2d2  0