The side length of a square is 5. If the side length increases X and the area increases y, find the function expression between Y and X

The side length of a square is 5. If the side length increases X and the area increases y, find the function expression between Y and X

From the meaning of the question: y = (x + 5) 2-52 = x2 + 10x. So the function expression between Y and X is y = x2 + 10x