A、$$\hat{b}_1 = \frac{\sum (x - \bar{x}) y}{\sum (x - \bar{x})^2}$$
B、$$\hat{b}_1 = \frac{\sum (x - \bar{x})(y - \bar{y})}{\sum (x - \bar{x})^2}$$
C、$$\hat{b}_1 = \frac{\sum xy}{\sum x^2}$$
D、$$\hat{b}_1 = \frac{\sum xy - n \bar{x} \bar{y}}{\sum x^2 - n \bar{x}^2}$$
E、$$\hat{b}_1 = \frac{n \sum xy - \sum x \sum y}{n \sum x^2 - (\sum x)^2}$$