Verified Solution • 2025–26 Session moderate

QJEEM23Maf853: JEE Main 2023 Mathematics - Class 12 JEEM23Maf853 Solution: If A and B are two non-zero n n matrices such that , then :

If A and B are two non-zero n ×\times n matrices such that A2+B=A2B\mathrm{A^2+B=A^2B} , then :

Multiple Choice Options

  • A A2B=I\mathrm{A^2B=I}
  • B A2=I\mathrm{A^2=I} or B=I\mathrm{B=I}
  • C A2B=BA2\mathrm{A^2B=BA^2}
  • D AB=I\mathrm{AB=I}

Step-by-Step Verified Solution

Given : A2+B=A2B...(i)A^{2}+B=A^{2} B\quad...(i)

⇒A2+B−I=A2B−I\Rightarrow A^{2}+B-I=A^{2} B-I

⇒A2B−A2−B+I=I\Rightarrow A^{2} B-A^{2}-B+I=I

⇒A2(B−I)−I(B−I)=I\Rightarrow A^{2}(B-I)-I(B-I)=I

⇒(A2−I)(B−I)=I\Rightarrow\left(A^{2}-I\right)(B-I)=I

∴A2−I\therefore A^{2}-I is the inverse matrix of B−IB-I and vice versa.

So, (B−I)(A2−I)=I(B-I)\left(A^{2}-I\right)=I

⇒BA2−B−A2+I=I\Rightarrow B A^{2}-B-A^{2}+I=I

∴A2+B=BA2...(ii)\therefore A^{2}+B=B A^{2} \quad...(ii)

So, by (i) and (ii)

A2B=BA2A^{2} B=B A^{2}

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