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4.1 complex nubers — MATHS STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceMATHS4.1 complex nubers1 Mark
MCQ
If $\frac{{5( - 8 + 6i)}}{{{{(1 + i)}^2}}} = a + ib$, then$(a,\,b)$ equals
  • ✓
    $(15, 20)$
  • B
    $(20, 15)$
  • C
    $( - 15, 20)$
  • D
    None of these
✓

Answer

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

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