Maharashtra BoardEnglish MediumSTD 11 ScienceMathsComplex Numbers2 Marks
MCQ
The square roots of -8 i are
A
$2+2 i,-2+2 i$
B
$-2-2 i,-2+2 i$
C
$2-2 i, 2+2 i$
✓
$2-2 i,-2+2 i$
✓
Answer
Correct option: D.
$2-2 i,-2+2 i$
(D) Let $x+ i y=\sqrt{-8 i }$ $\Rightarrow x^2-y^2+2 x y i =-8 i$ $\therefore \quad x^2-y^2=0$ and $2 x y=-8$ Solving these equations, we get $x=2, y=-2$ and $x=-2, y=2$ $\therefore \quad$ Square roots are $2-2 i ,-2+2 i$.
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