Verified Solution • 2025–26 Session moderate

QJEEM24Ma7b2b: JEE Main 2024 Mathematics - Class 12 JEEM24Ma7b2b Solution: Let , where are column matrics, and If and is the sum of all…

Let A=[2amp;0amp;11amp;1amp;01amp;0amp;1],B=[B1,B2,B3]A=\left[\begin{array}{lll}2 & 0 & 1 \\ 1 & 1 & 0 \\ 1 & 0 & 1\end{array}\right], B=\left[B_1, B_2, B_3\right] , where B1,B2,B3B_1, B_2, B_3 are column matrics, and

AB1=[100],AB2=[230],AB3=[321]\mathrm{AB}_1=\left[\begin{array}{l}1 \\0 \\0\end{array}\right], \mathrm{AB}_2=\left[\begin{array}{l}2 \\3 \\0\end{array}\right], \quad \mathrm{AB}_3=\left[\begin{array}{l}3 \\2 \\1\end{array}\right]

If α=∣B∣\alpha=|B| and β\beta is the sum of all the diagonal elements of BB , then α3+β3\alpha^3+\beta^3 is equal to ____________.

Step-by-Step Verified Solution

A=[2amp;0amp;11amp;1amp;01amp;0amp;1]B=[B1, B2, B3]\mathrm{A}=\left[\begin{array}{lll}2 & 0 & 1 \\1 & 1 & 0 \\1 & 0 & 1\end{array}\right] \quad \mathrm{B}=\left[\mathrm{B}_1, \mathrm{~B}_2, \mathrm{~B}_3\right]

B1=[x1y1z1],B2=[x2y2z2],B3=[x3y3z3]\mathrm{B}_1=\left[\begin{array}{l}\mathrm{x}_1 \\\mathrm{y}_1 \\\mathrm{z}_1\end{array}\right], \quad \mathrm{B}_2=\left[\begin{array}{l}\mathrm{x}_2 \\\mathrm{y}_2 \\\mathrm{z}_2\end{array}\right], \quad \mathrm{B}_3=\left[\begin{array}{l}\mathrm{x}_3 \\\mathrm{y}_3 \\\mathrm{z}_3\end{array}\right]

AB1=[2amp;0amp;11amp;1amp;01amp;0amp;1][x1y1z1]=[100]\mathrm{AB}_1=\left[\begin{array}{lll}2 & 0 & 1 \\1 & 1 & 0 \\1 & 0 & 1\end{array}\right]\left[\begin{array}{l}\mathrm{x}_1 \\\mathrm{y}_1 \\\mathrm{z}_1\end{array}\right]=\left[\begin{array}{l}1 \\0 \\0\end{array}\right]

x1=1,y1=−1,z1=−1AB2=[2amp;0amp;11amp;1amp;01amp;0amp;1][x2y2z2]=[230]x2=2,y2=1,z2=−2AB3=[2amp;0amp;11amp;1amp;01amp;0amp;1][x3y3z3]=[321]x3=2,y3=0,z3=−1 B=[1amp;2amp;2−1amp;1amp;0−1amp;−2amp;−1]α=∣B∣=3β=1α3+β3=27+1=28\begin{gathered}\mathrm{x}_1=1, \mathrm{y}_1=-1, \mathrm{z}_1=-1 \\\mathrm{AB}_2=\left[\begin{array}{lll}2 & 0 & 1 \\1 & 1 & 0 \\1 & 0 & 1\end{array}\right]\left[\begin{array}{l}\mathrm{x}_2 \\\mathrm{y}_2 \\\mathrm{z}_2\end{array}\right]=\left[\begin{array}{l}2 \\3 \\0\end{array}\right] \\\mathrm{x}_2=2, \mathrm{y}_2=1, \mathrm{z}_2=-2 \\\mathrm{AB}_3=\left[\begin{array}{lll}2 & 0 & 1 \\1 & 1 & 0 \\1 & 0 & 1\end{array}\right]\left[\begin{array}{l}\mathrm{x}_3 \\\mathrm{y}_3 \\\mathrm{z}_3\end{array}\right]=\left[\begin{array}{l}3 \\2 \\1\end{array}\right] \\\mathrm{x}_3=2, \mathrm{y}_3=0, \mathrm{z}_3=-1 \\\mathrm{~B}=\left[\begin{array}{ccc}1 & 2 & 2 \\-1 & 1 & 0 \\-1 & -2 & -1\end{array}\right] \\\alpha=|\mathrm{B}|=3 \\\beta=1 \\\alpha^3+\beta^3=27+1=28\end{gathered}

Related Learning Resources & Exam Preparation