Which values of x and y would make the following expression represent a real number? (6 + 3i) (x + yi) Options: x = 6, y = 0 x = - 3, y = 0 x = 6, y = - 3 x = 0, y = - 3

Question

Mathematics

Elliot Jackson

27 November, 14:17

Which values of x and y would make the following expression represent a real number? (6 + 3i) (x + yi) Options: x = 6, y = 0 x = - 3, y = 0 x = 6, y = - 3 x = 0, y = - 3

+4

Answers (2)

Know the Answer?

Asia Woodward · Answer 1

(x + yi) must be the conjugate of the complex number (6 + 3i).

⇒ x + yi = 6 - 3i

⇒ x = 6 and y = - 3 Verification: (6 + 3i) (6 - 3i) = 6² - (3i) ² = 36 + 9 = 45 ∈ RAttention! i² = - 1

Desmond Hunt · Answer 2

The answer is option 3. or C.

x = 6, y = - 3