Hi!
To solve this exercise, we can analyze the sides of this rectangle, which indicate the size of each side.
Let's do it:
On the superior side, we have: x+x+x+x+1, which means 4x+1, right?
On the left side, we have: x+x+1+1+1, or 2x+3
So, we can say that the factors of this rectangle are (4x+1)*(2x+3), last alternative.
