<s>[INST] Calculus Integral $\int \frac{dt}{2^{t} + 4}$ 
I try resolve this integral, with  $u = 2^t + 4 $, but can´t ... plz 
  $$\int \frac{dt}{2^t + 4} = \frac{1}{\ln 2}\int\frac{du}{u(u-4)} = \text{??} $$

 [/INST] Hint:
$$\frac{1}{2^x+4}=\frac{2^x-2^x+4}{4(2^x+4)}=\frac{1}{4} \left(1-\frac{2^x}{2^x+4}\right)$$
</s>