Todd and his brother Robert are going to use 512 square feet of their backyard for skateboard ramps. The shape of the backyard is rectangular, with the length twice as long as the width. What are the dimensions of the backyard?

Which quadratic equation would be used to solve for the unknown dimensions?

0 = 2w2
512 = w2
512 = 2w2
512 = 2l + 2w