The area, A, of a square is a function of the length, x, of a side of the square. Which of the following expresses this function, A(x), and the value at x = 2.5 cm? 1. a(x)=x^2; 6.25cm^2
2. a(x)=4x^2; 25cm^2
3. a(x)=2x; 5cm^2
4. a(x)=4x; 10cm^2