江画工太猩院 设/= 二阶可导, y=y(t), dy__y(t dy o(ty(t-o" (t)y'(o dr o'(t) dx k g(y"()-g"(ty()l o(0+y(o江西理工大学理学院 , ( ), ( ), 设 二阶可导 ⎩⎨⎧ == y t x t ψϕ . [ ( ) ( )] ( ) ( ) ( ) ( ) 2 3 2 2 t t t t t t k ϕ ψ ϕ ψ ϕ ψ ′ + ′ ′ ′′ − ′′ ′ ∴ = , ( ) ( ) t t dx dy ϕ ψ ′ ′ Q = . ( ) ( ) ( ) ( ) ( ) 2 3 2 t t t t t dx d y ϕ ϕ ψ ϕ ψ ′ ′ ′′ − ′′ ′ =