CSCA Exam › Mathematics › Geometry and algebra Reviewed CSCA Mathematics question · Easy What is the value of (1 + 2i)^2? -3 + 4i 1 + 4i 5 + 4i -3 - 4i Show the answer and explanation Correct answer A. -3 + 4i
Principle or equation Use the formula (a + bi)^2 = a^2 - b^2 + 2abi, with i^2 = -1.
Why this answer is correct Compute (1 + 2i)^2 = 1^2 + 2*1*2i + (2i)^2 = 1 + 4i + 4i^2 = 1 + 4i - 4 = -3 + 4i.
Example For (2 + i)^2 = 4 + 4i + i^2 = 3 + 4i.
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