Home › CBSE Class 11 › mathematics › Complex Numbers — Algebra, Powers of i, Modulus, Conjugate, Multiplicative Inverse, Argand Plane › Compute (3 + 5i)(2 + 6i).
Compute (3 + 5i)(2 + 6i).
A6 + 30
B-24 + 28i
C36 + 28i
D6 + 30i
Answer & Solution
Correct answer: B. -24 + 28i
(a + ib)(c + id) = (ac - bd) + i(ad + bc). Here: ac - bd = 3×2 - 5×6 = 6 - 30 = -24. ad + bc = 3×6 + 5×2 = 18 + 10 = 28. Result = -24 + 28i.
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