Factoring a quadratic polynomial, $4T^{2}-48T+144$

Question

The question is asking me to factor the following polynomial to the simplest form. (without making it messy) \begin{align*} & 4T^{2}-48T+144\\ \end{align*} Here is how I do it but not sure which ending is the most appropriate. \begin{align*} & 4T^{2}-48T+144\\ &=4\left ( T^{2}-12T+36 \right ) \\ &=4\left [ \left ( T^{2}-6T \right ) + \left ( -6T+36 \right )\right ] \\ &=4\left [ T\left ( T-6 \right )-6\left (T-6 \right ) \right ] \\ &=4\left ( T-6 \right )\left ( T-6 \right ) \end{align*} I know $4\left ( T-6 \right )\left ( T-6 \right )$ is equal to $4\left ( T-6 \right )^{2}$ but I don't know which one is simpler. I assume my answer is simpler as it has no power but the book answers $4\left ( T-6 \right )^{2}$. Any help is appreciated