Skip to content
Miscellaneous Exercise 4(B) · Q185

Q.Find matrices A and B, where 2A−B=[1−101]2A-B=\begin{bmatrix}1 & -1\\0 & 1\end{bmatrix} and A+3B=[1−101]A+3B=\begin{bmatrix}1 & -1\\0 & 1\end{bmatrix}

Maharashtra MsbshseTextbookSubjectiveImportance★★★★★est
87% · 185/212 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 →

Let M=[1−101]M=\begin{bmatrix}1 & -1\\0 & 1\end{bmatrix} (the book prints the SAME target matrix for both equations). Given: 2A−B=M2A-B=M ... (1); A+3B=MA+3B=M ... (2).

From (1): B=2A−MB=2A-M. Substitute into (2): A+3(2A−M)=M⇒A+6A−3M=M⇒7A=4M⇒A=47M=[4/7−4/704/7]A+3(2A-M)=M\Rightarrow A+6A-3M=M\Rightarrow 7A=4M\Rightarrow A=\tfrac47 M=\begin{bmatrix}4/7 & -4/7\\0 & 4/7\end{bmatrix}.

Then B=2A−M=[8/7−1−8/7+108/7−1]=[1/7−1/701/7]B=2A-M=\begin{bmatrix}8/7-1 & -8/7+1\\0 & 8/7-1\end{bmatrix}=\begin{bmatrix}1/7 & -1/7\\0 & 1/7\end{bmatrix}. …

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.