A farmer has 100 m of fencing to enclose a rectangular pen. Which quadratic equation gives the area (A) of the pen, given its width (w)?

1. A(w) = w2 – 50w
   
2. A(w) = w2 – 100w
   
3. A(w) = 50w – w2
   
4. A(w) = 100w – w2