2(1−e−2)2\left(1-e^{-2}\right)2(1−e−2)
(2(e−2−1)\left(2\left(e^{-2}-1\right)\right.(2(e−2−1)
12(e−2−1)\frac{1}{2}\left(e^{-2}-1\right)21(e−2−1)
12(1−e−2)\frac{1}{2}\left(1-e^{-2}\right)21(1−e−2)