By definition, a Perfect square is a number that is the square of an Integer.
In this case, you have the following expression given in the exercise:
![169-4d^2](https://img.qammunity.org/2023/formulas/mathematics/college/ul9k14z065jfgscchh5ranyhfzua3cdpv6.png)
You can identify that:
![169=13\cdot13=13^2](https://img.qammunity.org/2023/formulas/mathematics/college/zeek5qy5n6gp9qepubfrobs1osizkdlo3l.png)
Therefore, it is a Perfect square.
Notice that:
![4d^2=(2d)^2](https://img.qammunity.org/2023/formulas/mathematics/college/5018bfkcln7ntjplqvr37oc804eqt8px0f.png)
Therefore, it is a Perfect square.
For this case you must apply the Difference of two squares is:
![a^2-b^2=(a+b)(a-b)](https://img.qammunity.org/2023/formulas/mathematics/college/nj06qe3w5n12tlj39kazbxk0aehiwwpk6h.png)
Then, you can factor the expression:
![=-(2d-13)(2d+13)](https://img.qammunity.org/2023/formulas/mathematics/college/y04d9ailx4beu02pozgi8lq9h54p5oc5oh.png)
The answers are:
- Factored expression:
![-(2d-13)(2d+13)](https://img.qammunity.org/2023/formulas/mathematics/college/q578rqx2x5f9duq8dm8waib5p5hkb6nb00.png)
- ´Perfect squares:
![\begin{gathered} 169=13^2 \\ 4d^2=(2d)^2 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/bksm12gzsj8er5537dnqcdlnfk32skkpwc.png)