(5)复合函数若o(x)=0的实根x(k=1,2,3)全部是单根,则 [0(x)] S(x-xH (x) x1=0,9)(x1)= 6(x2-a2) (x-a)+6(x+a) x2-a2=(x+a)(x-a)=0,x (x2-a 2 3.其它表示 d(x)=lim rect(); 1→>0l I sin Kx d(x=lim d(x)=lim p8 tx(5) 复合函数 若 (x) = 0 的实根 xk (k =1,2,3, ) 全部是单根，则  − = k k k x x x x '( ) ( ) [ ( )]     例 ; ( ) ( ) 0, '( ) 1 1 a x ax x x a   =  = = . 2 ( ) ( ) ( ) 2 2 a x a x a x a − + + − =    x a x a a x a x a x a x a x a x x ( )' ( )' 2 ( )( ) 0, , 1 2 2 2 2 2 1 2 2 2 − = − = − = + − = = = − 3. 其它表示 ( ); 1 ( ) lim 0 l x rect l x l→  = ; 1 sin ( ) lim x Kx x K   → = . 1 ( ) lim 2 2 0 x x + = →     