Let a = 8i + 2j, b = –3i + j, and c = 2i – 5j, where i and j are unit vectors.What is 4a + 2b – 9c in terms of i and j?

Multiply each vector by its coefficient: 4a = 32i + 8j, 2b = −6i + 2j, and −9c = −18i + 45j. Add the i-components and j-components separately: (32 − 6 − 18)i + (8 + 2 + 45)j = 8i + 55j. The correct choice is D, 8i + 55j.

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