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CUET · MATHS · PYQ PAPER 2023

If \(a, b\) and \(c\) are all different from zero and \(\left|\begin{array}{ccc}1+a & 1 & 1 \\ 1 & 1+b & 1 \\ 1 & 1 & 1+c\end{array}\right|=0\), then the value of \(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\) is :

  1. A \(0\)
  2. B abc
  3. C \(-1\)
  4. D \(\frac{1}{a b c}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(-1\)

Step-by-step Solution

Detailed explanation

\( R_1 \rightarrow R_1 - R_2, R_2 \rightarrow R_2 - R_3 \) \( \left|\begin{array}{ccc}a & -b & 0 \\ 0 & b & -c \\ 1 & 1 & 1+c\end{array}\right|=0 \) \( a(b(1+c) - (-c)(1)) + 1((-b)(-c) - 0(b)) = 0 \) \( ab+abc+ac+bc = 0 \) \( \frac{ab+abc+ac+bc}{abc} = 0 \)…
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