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Complex Numbers — Maths STD 11 Science — Question

Maharashtra BoardEnglish MediumSTD 11 ScienceMathsComplex Numbers2 Marks
MCQ
If $\frac{5(-8+6 i)}{(1+i)^2}=a+i b$, then $(a, b)$ equals
  • ✓
    $(15,20)$
  • B
    $(20,15)$
  • C
    $(-15,20)$
  • D
    $(-15,-20)$
✓

Answer

Correct option: A.
$(15,20)$
(A)
$\frac{5(-8+6 i)}{(1+i)^2}=a+i b$
$\Rightarrow \frac{-40+30 i }{2 i }=15+20 i = a + ib$
Equating real and imaginary parts, we get $a =15$ and $b =20$

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