NCERT Class 12 · Ch 3 Exercise 3.2 · Q21
NCERT Class 12 Maths · Chapter 3 Matrices · Exercise 3.2 Question 21
Let X,Y,Z,W,P have orders 2×n,3×k,2×p,n×3,p×k respectively. What restrictions make PY+WY defined?
💡 Concept Hints
- Check the matrix orders and the meaning of the requested operation before calculating.
- Keep row and column indices in order. Compare corresponding entries only after the matrix expressions have compatible dimensions.
✅ Step-by-Step Solution
Final Answer: A: k=3 and p=n.
- PY is defined only when the columns of P equal the rows of Y: k=3. Its output order is p×k.
- WY is defined because W has 3 columns and Y has 3 rows; its order is n×k.
- Addition requires p×k and n×k to agree, so p=n. Select A.
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