解:◎建立坐标系并写出弯矩方程 M(x)= P(x-a)(0≤x≤a) 0 (a≤x≤L) f e写出微分方程的积分并积分 P(a-x)(0≤x≤a) E”=0 (a≤x≤L EIf-P(a-x)2+C Elf=6 P(a-x+Cix+c 2 D Dx+解：建立坐标系并写出弯矩方程      −   = 0 ( ) ( ) (0 ) ( ) a x L P x a x a M x 写出微分方程的积分并积分      − − +  = 1 1 2 ( ) 2 1 D P a x C EIf      + − + + = 1 2 1 2 3 ( ) 6 1 D x D P a x C x C EIf      −    = 0 ( ) ( ) (0 ) a x L P a x x a EIf x f P L a