15.设y=tan2(1+2x2),则d= y=2tan(1+2x2)-sec2(1+2x2)4x dy 8xtan(1+2x2).sec2(1+2x2)dx 16.设函数)在x=处可导，1m)-/-力-1 h->0 2h 则f'(x)= 1m/）-f-2=1mf--/x】 h->0 2h h0 -2h 7f'(x)=-1 f'(x)=-2 2 2 15.设y x dy = + = tan (1 2 ),则 0 0 0 0 0 ( ) ( ) ( ) lim 1 2 ( ) h f x f x h f x x x h f x → − − = = −  = 16.设函数 在 处可导, 则 2 2 2 y x x x  = +  +  2tan(1 2 ) sec (1 2 ) 4 2 2 2 dy x x x dx = +  + 8 tan(1 2 ) sec (1 2 ) 0 f x ( ) 2 = − 0 0 0 0 0 0 ( ) ( ) ( ) ( ) lim lim h h 2 2 f x f x h f x h f x → → h h − − − − = − 0 1 ( ) 1 2 = = − f x 