5×^√16 - 2×^√(-216) - ^√64
5×4 - 2×√(-216) - √64
20 - 2×√(-216) - 8
20 - 2×(√216)i - 8
12 - 2×(√216)i
12 - 2×6√6i
12 - 12√6i
Therefore, the final simplified expression is 12 - 12√6i.
5×^√16 - 2×^√(-216) - ^√64
5×4 - 2×√(-216) - √64
20 - 2×√(-216) - 8
20 - 2×(√216)i - 8
12 - 2×(√216)i
12 - 2×6√6i
12 - 12√6i
Therefore, the final simplified expression is 12 - 12√6i.