q R= R B B X R A R Q(x)=ra-gx B 9292 q (0<x< X M(x) x- gx 276 yh 2 12,q X 2 2 (0≤xsU8R R q l A = B = 2 Q x R qx q l ( ) = A − = − qx 2 M x q l x qx x ( ) = − 2 2 RA RB CL7TU8 A B l x q (0  x  l) = − −       + q x l q l 2 2 8 2 2 (0  x  l) Q M q l 2 q l 2 q l 2 8