The correct answer is: A. 1 and 2
The normal equation is a method for solving a system of linear equations. It is a direct method, which means that it does not require any iterative steps. This makes it faster than iterative methods, such as the Gauss-Seidel method, when the number of equations is small. However, the normal equation becomes slower when the number of equations is large. This is because the normal equation requires inverting a matrix, which is a computationally expensive operation.
The normal equation is also a closed-form solution, which means that it can be written in a simple formula. This makes it easy to understand and implement. However, the normal equation is not always the most accurate solution. This is because it assumes that the data is noise-free. In reality, data always contains some noise. This noise can cause the normal equation to give inaccurate results.
In conclusion, the normal equation is a fast and easy-to-use method for solving a system of linear equations. However, it is not always the most accurate solution.
Here is a brief explanation of each option:
- We don’t have to choose the learning rate.
The learning rate is a parameter that is used in iterative methods, such as the Gauss-Seidel method. It controls how quickly the algorithm converges to a solution. The normal equation does not require a learning rate, because it is a direct method.
- It becomes slow when number of features is very large.
The normal equation requires inverting a matrix. This is a computationally expensive operation, and it becomes more expensive as the number of features increases. Therefore, the normal equation becomes slow when the number of features is very large.
- No need to iterate.
The normal equation is a direct method, which means that it does not require any iterative steps. This makes it faster than iterative methods, such as the Gauss-Seidel method, when the number of equations is small.