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CUET · MATHS · PYQ PAPER 2025

If \(\left|\begin{array}{ccc}1+a & 1 & 1 \\ 1 & 1+b & 1 \\ 1 & 1 & 1+c\end{array}\right|\), where \(a, b\) and \(c\) are non zero constants, then the value of \(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\) is

  1. A \(-1\)
  2. B 1
  3. C \(0\)
  4. D abc
Verified Solution

Answer & Solution

Correct Answer

(A) \(-1\)

Step-by-step Solution

Detailed explanation

\(\left|\begin{array}{ccc}1+a & 1 & 1 \\ 1 & 1+b & 1 \\ 1 & 1 & 1+c\end{array}\right| = (1+a)((1+b)(1+c)-1) - 1(1(1+c)-1) + 1(1-1(1+b))\) \( = (1+a)(1+b+c+bc-1) - (1+c-1) + (1-1-b)\) \( = (1+a)(b+c+bc) - c - b\) \( = b+c+bc+ab+ac+abc - c - b\) \( = ab+bc+ac+abc\)…