Multiply each pair of conjugates

(2 sqrt6 + 8) (2 sqrt6 - 8)

Answer: - 40

Step-by-step explanation:

(2 sqrt6 + 8) (2 sqrt6 - 8)

(2√6 + 8) (2√6 - 8)

2√6 (2√6 - 8) + 8 (2√6 - 8)

(2√6) ^2 + (2√6 * - 8) + (8 * 2√6) + (8 * - 8)

(4 * 6) + (-16√6) + (16√6) + (-64)

24 - 16√6 + 16√6 - 64

24 - 64

-40