Let's break down the problem step by step. The task requires calculating the largest rectangle of concrete a landscaper can make in their backyard. The area $A$ of the concrete pad with length $x$ meters is given by the formula $A(x)$.

The Questions:

1. What is the length of the pad when $x = 6$ meters?
2. What is the area of the pad when $x = 7$ meters?
3. What is the pad's length if the landscaper will achieve maximum area?
4. What is the maximum area of the pad?
5. Draw a graph of the model.

Since I need to calculate the answers, could you please provide the explicit formula for $A(x)$? The image states that the formula is given, but it isn't visible in the upload.

Once I have the formula, I can proceed with solving all the questions.