Evaluating limit involving logarithm

107 Views Asked by At

enter image description here

I understand why (24) and (25) are true, but did not understand why (26) is true? For full details please see the following paper

1

There are 1 best solutions below

0
On BEST ANSWER

$\ln\left(1+\frac{1}{a}\sum_{t=1}^Tx_t^2\right)=\ln\left(1+\frac{1}{a}\sum_{t=1}^T2^{2(t-1)}\right)=\ln(1)-\ln(a)+\ln \sum_{t=1}^T2^{2(t-1)}=0-\ln(a)+\prod_{t=1}^T2\ln2^t-\prod_{t=1}^T2\ln4=2T\ln2 + \mathcal{O}(1)$