$2+\frac{1}{e}$

$e^2+\frac{1}{2}$

$\frac{1}{e^2}+2$

$e+\frac{1}{e}$

$-e^{\frac{-\pi}{4}}$

$\sqrt{2} e^{\frac{\pi}{4}}$

$\sqrt{2} e^{\frac{-\pi}{4}}$

$e^{\frac{-\pi}{4}}$

$1+\sec ^2 x$

$\frac{1}{1+\sec ^2 f(x)}$

$\frac{1}{1+\sec ^2 g(x)}$

$1+\sec ^2 f(x)$

$-\sqrt{\frac{y-y^2}{x-x^2}}$

$-\sqrt{\frac{1-y^2}{1-x^2}}$

$-\sqrt{\frac{1-y}{1-x}}$

$-\sqrt{\frac{x-y}{x+y}}$