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QJEEAdv22Ma5860: JEE Advanced 2022 Mathematics - Class 12 JEEAdv22Ma5860 Solution: If , then which of the following matrices is equal to

If M=(52amp;32−32amp;−12)M=\left(\begin{array}{rr}\frac{5}{2} & \frac{3}{2} \\ -\frac{3}{2} & -\frac{1}{2}\end{array}\right) , then which of the

following matrices is equal to M2022?M^{2022} ?

Multiple Choice Options

  • A (30343033−3033−3032)\left(\begin{array}{rr}3034 & 3033 \\ -3033 & -3032\end{array}\right)
  • B (3034−30333033−3032)\left(\begin{array}{ll}3034 & -3033 \\ 3033 & -3032\end{array}\right)
  • C (30333032−3032−3031)\left(\begin{array}{rr}3033 & 3032 \\ -3032 & -3031\end{array}\right)
  • D (30323031−3031−3030)\left(\begin{array}{rr}3032 & 3031 \\ -3031 & -3030\end{array}\right)

Step-by-Step Verified Solution

A=(52amp;32−32amp;−12)A=\left(\begin{array}{cc}\frac{5}{2} & \frac{3}{2} \\ -\frac{3}{2} & -\frac{1}{2}\end{array}\right)

A2=(4amp;3−3amp;−2)A^{2}=\left(\begin{array}{cc}4 & 3 \\ -3 & -2\end{array}\right)

A3=(112amp;92−92amp;−72)A^{3}=\left(\begin{array}{cc}\frac{11}{2} & \frac{9}{2} \\ -\frac{9}{2} & -\frac{7}{2}\end{array}\right)

A4=(7amp;6−6amp;−5)A^{4}=\left(\begin{array}{cc}7 & 6 \\ -6 & -5\end{array}\right)

and so on

An=(3n2+1amp;3n2−3n2amp;−3n2+1)A^n=\left(\begin{array}{cc}\frac{3 n}{2}+1 & \frac{3 n}{2} \\ -\frac{3 n}{2} & -\frac{3 n}{2}+1\end{array}\right)

Now

A2022amp;=(3×20222+1amp;3×20222−3×20222amp;−3×20222+1)amp;=(3034amp;3033−3033amp;−3032)\begin{aligned}A^{2022} & =\left(\begin{array}{ll}\frac{3 \times 2022}{2}+1 & \frac{3 \times 2022}{2} \\\frac{-3 \times 2022}{2} & \frac{-3 \times 2022}{2}+1\end{array}\right) \\\\& =\left(\begin{array}{cc}3034 & 3033 \\-3033 & -3032\end{array}\right)\end{aligned}

∴\therefore Option (A)(\mathrm{A}) is correct

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