I'm having trouble to understand the consign of the exercise. It says "Approximate the data of the following table with a model of the form ~ in the meaning of least squares for the function .

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My approach : I believe they ask me to approximate the data in the table, with a function of the form , so I wonder what the is about. So I didn't considered it. I made the least squares, that is . I did the partial derivative with respect to a and equaling it to 0 I got the following equation : , where is .

I did the same with the partial derivative with respect to b, except that I had to suppose and different from to make some division. And I got exactly the same equation as I got for the first partial derivative. Therefore the system has no solution, which is not normal considering the problem given. It means I made an error, or I misinterpreted the problem. Can you help me?