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NCERT Class 12 · Ch 3 Exercise 3.1 · Q4

NCERT Class 12 Maths · Chapter 3 Matrices · Exercise 3.1 Question 4

Construct 2×2 matrices for (1) aᵢⱼ=(i+j)²/2; (2) aᵢⱼ=i/j; (3) aᵢⱼ=(i+2j)²/2.

💡 Concept Hints

  1. Check the matrix orders and the meaning of the requested operation before calculating.
  2. Keep row and column indices in order. Compare corresponding entries only after the matrix expressions have compatible dimensions.

✅ Step-by-Step Solution

Final Answer: \(\left[\begin{matrix}2 & \frac{9}{2}\\\frac{9}{2} & 8\end{matrix}\right]\); \(\left[\begin{matrix}1 & \frac{1}{2}\\2 & 1\end{matrix}\right]\); \(\left[\begin{matrix}\frac{9}{2} & \frac{25}{2}\\8 & 18\end{matrix}\right]\)
  1. Use indices i=1,…,2 and j=1,…,2. Fill one row at a time.
  2. Part 1: aᵢⱼ=(i+j)²/2. For each fixed i, substitute every j in order; the resulting matrix is \(\left[\begin{matrix}2 & \frac{9}{2}\\\frac{9}{2} & 8\end{matrix}\right]\).
  3. Part 2: aᵢⱼ=i/j. For each fixed i, substitute every j in order; the resulting matrix is \(\left[\begin{matrix}1 & \frac{1}{2}\\2 & 1\end{matrix}\right]\).
  4. Part 3: aᵢⱼ=(i+2j)²/2. For each fixed i, substitute every j in order; the resulting matrix is \(\left[\begin{matrix}\frac{9}{2} & \frac{25}{2}\\8 & 18\end{matrix}\right]\).

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