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Matrices

Question
CBSEENMA12034271

If space space space straight A equals space open square brackets table row 3 1 row cell negative 1 end cell 2 end table close square brackets verify that A2 — 5A + 71 = O.

Solution
space Here space straight A equals space open square brackets table row 3 1 row cell negative 1 end cell 2 end table close square brackets
space space space space space space space space space space space straight A squared equals open square brackets table row 3 1 row cell negative 1 end cell 2 end table close square brackets space space space open square brackets table row 3 1 row cell negative 1 end cell 2 end table close square brackets space equals space open square brackets table row cell 9 minus 1 end cell cell 3 plus 2 end cell row cell negative 3 minus 2 end cell cell negative 1 plus 4 end cell end table close square brackets equals space open square brackets table row 8 5 row cell negative 5 end cell 3 end table close square brackets
space space space space straight L. straight H. straight S space equals space straight A squared space minus space 5 straight A space plus 71 space equals space open square brackets table row 8 5 row cell negative 5 end cell 3 end table close square brackets space minus 5 space open square brackets table row 3 1 row cell negative 1 end cell 2 end table close square brackets space plus 7 space open square brackets table row 1 0 row 0 1 end table close square brackets
space space space space space space space space space space space space space space space equals space open square brackets table row 8 5 row cell negative 5 end cell 3 end table close square brackets space plus space open square brackets table row 15 cell negative 5 end cell row 5 cell negative 10 end cell end table close square brackets plus space open square brackets table row 7 0 row 0 7 end table close square brackets
space space space space space space space space space space space space space space space equals space open square brackets table row cell 8 minus 15 plus 7 end cell cell 5 minus 5 plus 0 end cell row cell negative 5 plus 5 plus 0 end cell cell 3 minus 10 plus 7 end cell end table close square brackets space space equals space open square brackets table row 0 0 row 0 0 end table close square brackets equals straight O
space space space space space space space space space space space space space space equals space space straight R. straight H. straight S