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JEE Mains · Maths · STD 12 - 3 and 4 . metrices and determinant

यदि समीकरण निकाय\(x-2 y+5 z=0\), \(-2 x+4 y+z=0\), \(-7 x+14 y+9 z=0\) के पूर्णांकीय हलों \(( x , y , z )\) का समुच्चय \(S\) है, जिनके लिए \(15 \leq x ^{2}+ y ^{2}+ z ^{2} \leq 150\); तो \(S\) के अवयवों की संख्या है

  1. A \(16\)
  2. B \(-8\)
  3. C \(-16\)
  4. D \(8\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(8\)

Step-by-step Solution

Detailed explanation

\(\Delta=\left|\begin{array}{ccc}1 & -2 & 5 \\ -2 & 4 & 1 \\ -7 & 14 & 9\end{array}\right|=0\) Let \(\quad x=k\) \(\Rightarrow \quad\) Put in \((1)\;and\;(2)\) \(k-2 y+5 z=0\) \(-2 k+4 y+z=0\) \(z=0, y=\frac{k}{2}\) \(\therefore \quad x , y , z\) are integer…
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