Answer:
Option 3
Step-by-step explanation:
This is the same reason that Pythagorean's Theorem works. The area made up of the X and Y Regions (the squares of the two legs of the triangle) is equal to Region Z (the square of the hypotenuse)
We have that:
Let's name each side of it with f(x) and g(x):
Then, we have that:
Then, the answer is C