⑩天掌 Teaching Plan on Advanced Mathematics 若函数 x=φ(t) 二阶可导, y=y(t) dy_d中d,'(t)dt dx d dx dt op(t)dx y"(t(t)-y(to(t) 1 p(t) 即 dy y (to(t-y(to(t) 2 qp°(t)Tianjin Polytechnic University Teaching Plan on Advanced Mathematics , ( ) ( ) 若函数 二阶可导    =  =  y t x t ( ) 2 2 dx dy dx d dx d y = dx dt t t dt d ) ( ) ( ) (   = ( ) 1 ( ) ( ) ( ) ( ) ( ) 2 t t t t t t            −   = . ( ) ( ) ( ) ( ) ( ) 2 3 2 t t t t t dx d y         −   即 =