Integrate without substitution I'm wondering how I could integrate the following without substitution:$$\int \frac{4}{1 + e^{-x}}dx$$ 
I know we can factor out the constant so that $4 * \int \frac{1}{1 + e^{-x}}$ but I'm stumped as of what to do next. Could anyone help me out?

$$\int \frac{1}{1+\frac{1}{e^x}} dx = \int \frac{e^x}{1+ e^x} dx = \ln (1 + e^x) + C $$
