Skip to content
Worked Examples · Example 13

Q.Given that X2×nX_{2\times n}, Y3×kY_{3\times k}, Z2×pZ_{2\times p}, Wn×3W_{n\times 3} and Pp×kP_{p\times k} are matrices of specified order. What are the conditions

(i) for nn, kk and pp so that 3PY+2WY3PY + 2WY is defined
(ii) for the order of the matrix 2X−3Z2X - 3Z.
Puducherry CbseNCERTSubjective· 3mImportance★★★★★est
16% · 13/80 Questions
🔒 Locked · start free trial →

You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.

Start your 14-day free trial to unlock the full solution →

Use the multiplication rule (inner dimensions match) and the addition rule (same order) on the given symbolic orders.

Product Pa×b Qc×dP_{a\times b}\,Q_{c\times d} is defined only if b=cb=c, giving order a×da\times d. A sum/difference is defined only if the two matrices share the same order.

Given orders: X2×nX_{2\times n}, Y3×kY_{3\times k}, Z2×pZ_{2\times p}, Wn×3W_{n\times 3}, Pp×kP_{p\times k}.

  1. (i) Examine PYPY. PP is p×kp\times k and YY is 3×k3\times k; the product PYPY needs the inner dimensions equal: k=3k=3. Then YY is 3×33\times 3 and PYPY has order p×3p\times 3.
  2. Examine WYWY. WW is n×3n\times 3 and YY is 3×33\times 3; inner dimensions match (3=33=3), so WYWY has order n×3n\times 3.
  3. Add 3PY+2WY3PY+2WY. Addition requires equal orders: p×3=n×3 ⇒ p=np\times 3 = n\times 3\ \Rightarrow\ p=n. …

Unlock everything free for 14 days

  • Full step-by-step solutions
  • Concept-first explanations
  • Methods, shortcuts & mistakes
  • PYQ mapping + timed mock tests

Full access for 14 days. No credit card required.