fɔːɹ æz ɐ dˈɪfɚɹˌɛnʃɪəbəl fˈʌŋkʃən ænd æz ˌɛni kəntˈɪnjuːəs kˈɜːv ɪnwˌɪtʃ stˈɑːɹts æɾə pˈɔɪnt ænd ˈɛndz æɾə pˈɔɪnt , ðˈɛn
For  as a differentiable function and  as any continuous curve in  which starts at a point  and ends at a point , then