Answer:

Step-by-step explanation:
Split these into two separate squares.
One has side lengths of x + 3, and the other has side lengths of x + 1.
<u>We'll solve the first square first.</u>
Here is the expression we want to use:
* 
Use FOIL (first, outer, inner, last).

Simplify.

<u>Time for the second square!</u>
This goes similarly to the first one, so I'll omit any words and you can follow along with the math.
* 


<u>Now, we'll add them together.</u>

Combine like terms.

And we're done!