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Determinants

Question
CBSEENMA12034406

Using properties of determinats, prove the following:
open vertical bar table row straight a cell space straight b end cell cell space space straight c end cell row cell straight a minus straight b end cell cell space space space straight b minus straight c end cell cell space space space straight c minus straight a end cell row cell straight b plus straight c end cell cell space space straight c plus straight a end cell cell space space space straight a plus straight b end cell end table close vertical bar space equals space straight a cubed plus straight b cubed plus straight c cubed minus 3 abc.

Solution

L.H.S. = open vertical bar table row straight a cell space straight b end cell cell space space straight c end cell row cell straight a minus straight b end cell cell space space space straight b minus straight c end cell cell space space space straight c minus straight a end cell row cell straight b plus straight c end cell cell space space straight c plus straight a end cell cell space space space straight a plus straight b end cell end table close vertical bar space equals space open vertical bar table row cell straight a plus straight b plus straight c end cell cell space space space space straight a plus straight b plus straight c end cell cell space space straight a plus straight b plus straight c end cell row cell straight a minus straight b end cell cell straight b minus straight c end cell cell space straight c minus straight a end cell row cell straight b plus straight c end cell cell straight c plus straight a end cell cell straight a plus straight b end cell end table close vertical bar comma space by space straight R subscript 1 plus straight R subscript 3
        equals space left parenthesis straight a plus straight b plus straight c right parenthesis space open vertical bar table row 1 1 1 row cell straight a minus straight b end cell cell space straight b minus straight c end cell cell space straight c minus straight a end cell row cell straight b plus straight c end cell cell space straight c plus straight a end cell cell space space straight a plus straight b end cell end table close vertical bar
equals space left parenthesis straight a plus straight b plus straight c right parenthesis space open vertical bar table row 1 cell space space space space space 0 end cell 0 row cell straight a minus straight b end cell cell space space space space space space 2 straight b minus straight c minus straight a end cell cell space space space straight b plus straight c minus 2 straight a end cell row cell straight b plus straight c end cell cell space space space straight a minus straight b end cell cell space space straight a minus straight c end cell end table close vertical bar comma space by space straight C subscript 2 space minus space straight C subscript 1 comma space space straight C subscript 3 space minus space straight C subscript 1
equals space left parenthesis straight a plus straight b plus straight c right parenthesis space open vertical bar table row cell 2 straight b minus straight c minus straight a end cell cell space space space space space space straight b plus straight c minus 2 straight a end cell row cell straight a minus straight b end cell cell space space space space straight a minus straight c end cell end table close vertical bar
equals space left parenthesis straight a plus straight b plus straight c right parenthesis space open vertical bar table row cell straight b minus straight c end cell cell space space space straight b minus straight a end cell row cell straight a minus straight b end cell cell space space space straight a minus straight c end cell end table close vertical bar comma space by space straight R subscript 1 plus straight R subscript 2
equals left parenthesis straight a plus straight b plus straight c right parenthesis space open square brackets left parenthesis straight b minus straight c right parenthesis thin space left parenthesis straight a minus straight c right parenthesis space minus space left parenthesis straight a minus straight b right parenthesis thin space left parenthesis straight b minus straight a right parenthesis close square brackets
space equals left parenthesis straight a plus straight b plus straight c right parenthesis space open square brackets straight a space straight b space minus straight b space straight c minus straight c space straight a space plus space straight c squared plus straight a squared plus straight b squared minus 2 ab close square brackets
equals space left parenthesis straight a plus straight b plus straight c right parenthesis space left parenthesis straight a squared plus straight b squared plus straight c squared minus ab minus bc minus ca right parenthesis space equals space straight a cubed plus straight b cubed plus straight c cubed minus 3 abc
equals space straight R. straight H. straight S.

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