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Complex Numbers — Maths STD 11 Science — Question

CBSE BoardEnglish MediumSTD 11 ScienceMathsComplex Numbers2 Marks
Question
Express the following complex numbers in the standard form a + ib:
$(1+\text{i})(1+2\text{i})$
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Answer

$(1+\text{i})(1+2\text{i})=1\times(1+2\text{i})+\text{i}(1+2\text{i})$
$=1+2\text{i}+\text{i}+2\text{i}^2$
$=1+3\text{i}-2$
$=-1+3\text{i}$
$\therefore \ (1+\text{i})(1+2\text{i})=-1+3\text{i}$

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