The relationship between voltage, E, current, I, and resistance, Z, is given by the equation E = IZ. If a circuit has a current I = 3 + 2i and a resistance Z = 2 – i, what is the voltage of the circuit?

Use E = IZ and multiply the complex numbers: (3 + 2i)(2 − i) = 6 − 3i + 4i − 2i². Since i² = −1, this becomes 6 + i + 2 = 8 + i, so the voltage is choice C, 8 + i.

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