Answer: B
\(\sum \limits_{i=1}^5 2x_i(x_i - 3)\) \(= \sum \limits_{i=1}^5 2x_i^2 - \sum \limits_{i=1}^5 6x_i\) \(= 2 \times \sum \limits_{i=1}^5 x_i^2 - 6 \times \sum \limits_{i=1}^5 x_i\) \(= 2 \times 14 - 6 \times 5\) \(= 28 - 30\) \(= -2\)
\(\sum \limits_{i=1}^5 2x_i(x_i - 3)\) \(= \sum \limits_{i=1}^5 2x_i^2 - \sum \limits_{i=1}^5 6x_i\) \(= 2 \times \sum \limits_{i=1}^5 x_i^2 - 6 \times \sum \limits_{i=1}^5 x_i\) \(= 2 \times 14 - 6 \times 5\) \(= 28 - 30\) \(= -2\)