Answer:
The second one; x²+7x+12
Step-by-step explanation:
So, since the beginning lengths of the square is x and x, the area of the square is x².
But then, you add 3 to one length, so that side is now (x+3), and then you add 4 to the width, so that is now (x+4).
Finally, you would multiply them together to get the equation you would use to find the new area.
For this, you would cross-multiply everything together; the x in the length by the x in the width, the x in the length by the 4 in the width, the 3 in the length by the x in the width, and then the 3 in the length by the 4 in the width. Now, all you have to do is add all of these together to get your answer.
Here's the work: