Prove that: from Mathematics Determinants

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 Multiple Choice QuestionsShort Answer Type

121.

Solve the equation
open vertical bar table row cell straight x plus straight a end cell cell space straight x end cell cell space straight x end cell row straight x cell space straight x plus straight a end cell cell space straight x end cell row straight x straight x cell space straight x plus straight a end cell end table close vertical bar space equals space 0 comma space space space straight a not equal to space 0.

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 Multiple Choice QuestionsLong Answer Type

122.

Solve:
open vertical bar table row cell straight x plus 1 end cell 2 3 row 3 cell straight x plus 2 end cell 1 row 1 2 cell straight x plus 3 end cell end table close vertical bar space equals 0

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123.

Prove that:
open vertical bar table row cell straight a squared plus 1 end cell cell straight a space straight b end cell cell straight a space straight c end cell row cell straight a space straight b end cell cell straight b squared plus 1 end cell cell straight b space straight c end cell row cell straight a space straight c end cell cell straight b space straight c end cell cell straight c squared plus 1 end cell end table close vertical bar space equals space 1 plus straight a squared plus straight b squared plus straight c squared.

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 Multiple Choice QuestionsShort Answer Type

124.

If x, y, z are different and
increment space equals space open vertical bar table row straight x cell space space space space straight x squared end cell cell space 1 plus straight x cubed end cell row straight y cell space space space straight y squared end cell cell space 1 plus straight y cubed end cell row straight z cell space space straight z squared end cell cell space 1 plus straight z cubed end cell end table close vertical bar space equals space 0 comma space space then space show space that space 1 plus xyz space equals 0

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 Multiple Choice QuestionsLong Answer Type

125.

Prove that:
open vertical bar table row straight x cell space space space straight x squared end cell cell space space 1 plus px cubed end cell row straight y cell space space straight y squared end cell cell space space 1 plus py cubed end cell row straight z cell space space straight z squared end cell cell space space 1 plus pz cubed end cell end table close vertical bar space equals space left parenthesis 1 plus pxyz right parenthesis thin space left parenthesis straight x minus straight y right parenthesis thin space left parenthesis straight y minus straight z right parenthesis thin space left parenthesis straight z minus straight x right parenthesis
where p is any scalar.

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 Multiple Choice QuestionsShort Answer Type

126.

If space open vertical bar table row straight a cell space space straight a cubed end cell cell space space straight a to the power of 4 minus 1 end cell row straight b cell space straight b cubed end cell cell space space straight b to the power of 4 minus 1 end cell row straight c cell space straight c cubed end cell cell space space straight c to the power of 4 minus 1 end cell end table close vertical bar space equals space 0 comma
show that
a + b + c = abc(ab + bc + ca) where a , b , c are all different.

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127.

Let the three digit numbers A28,3B9 and 62C where A, B, and C are any integers between 0 and 9, be divisible by a fixed integer k. Show that the determinant
open vertical bar table row straight A cell space space 3 end cell cell space space space 6 end cell row 8 cell space 9 end cell cell space space straight C end cell row 2 cell space straight B end cell cell space space 2 end cell end table close vertical bar
is divisible by k.

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 Multiple Choice QuestionsLong Answer Type

128.

Prove that:
open vertical bar table row cell left parenthesis straight b plus straight c right parenthesis squared end cell cell straight a squared end cell cell straight a squared end cell row cell straight b squared end cell cell left parenthesis straight c plus straight a right parenthesis squared end cell cell straight b squared end cell row cell straight c squared end cell cell straight c squared end cell cell left parenthesis straight a plus straight b right parenthesis squared end cell end table close vertical bar space equals space 2 space abc space left parenthesis straight a plus straight b plus straight c right parenthesis cubed.

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129.

Prove that:
open vertical bar table row cell negative 2 straight a end cell cell space space space space straight a plus straight b end cell cell space space space straight a plus straight c end cell row cell straight b plus straight a end cell cell space space minus 2 straight b end cell cell space space space straight b plus straight c end cell row cell straight c plus straight a end cell cell space space straight c plus straight b end cell cell space space minus 2 straight c end cell end table close vertical bar space equals space 4 left parenthesis straight a plus straight b right parenthesis thin space left parenthesis straight b plus straight c right parenthesis thin space left parenthesis straight c plus straight a right parenthesis.



Let space increment space equals space open vertical bar table row cell negative 2 straight a end cell cell space space space space space space straight a plus straight b end cell cell space space space space straight a plus straight c end cell row cell straight b plus straight a end cell cell space space minus 2 straight b end cell cell space space space straight b plus straight c end cell row cell straight c plus straight a end cell cell space straight c plus straight b end cell cell space space space minus 2 straight c end cell end table close vertical bar space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space... left parenthesis 1 right parenthesis
Putting space straight a plus straight b space equals space 0 space space space or space space straight a space equals negative straight b space in space left parenthesis 1 right parenthesis comma space we space get comma
increment space equals space open vertical bar table row cell 2 straight b end cell cell space space 0 end cell cell space space space space straight c minus straight b end cell row 0 cell space space minus 2 straight b end cell cell space space space space straight b plus straight c end cell row cell straight c minus straight b end cell cell space space space straight c plus straight b end cell cell space space space minus 2 straight c end cell end table close vertical bar
space space space space equals space 2 straight b open vertical bar table row cell negative 2 straight b end cell cell space space space space space space space space space space straight b plus straight c end cell row cell straight c plus straight b end cell cell space space space space space space minus 2 straight c end cell end table close vertical bar plus left parenthesis straight c minus straight b right parenthesis space open vertical bar table row 0 cell space space space space space space space minus 2 straight b end cell row cell straight c minus straight b end cell cell space space space space space space space space space straight c plus straight b end cell end table close vertical bar
space space space space space equals space 2 space straight b open square brackets 4 space straight b space straight c space minus straight b squared minus straight c squared minus 2 space straight b space straight c close square brackets space plus space left parenthesis straight c minus straight b right parenthesis space left square bracket 0 plus 2 space straight b space straight c minus 2 space straight b squared right square bracket
space space space space equals 2 space straight b space left parenthesis negative straight b squared minus straight c squared plus 2 bc right parenthesis plus left parenthesis straight c minus straight b right parenthesis thin space left parenthesis 2 space straight b space straight c space minus space 2 space straight b squared right square bracket
space space space space equals space minus 2 straight b cubed minus 2 bc squared plus 4 straight b squared straight c minus 2 bc squared minus 2 straight b squared straight c minus 2 straight b squared straight c plus 2 straight b cubed
space space space space space equals space 0
therefore space space space space space space space straight a plus straight b minus 0 space space space space space straight i. straight e. space space space straight a plus straight b space is space straight a space factor space of space increment
Similarly space straight b plus straight c comma space space space straight c plus straight a space space space space are space factors space of space increment.
Now space increment space is space of space 3 rd space degree
therefore space space space space space space increment space equals space straight k space left parenthesis straight a plus straight b right parenthesis thin space left parenthesis straight b plus straight c right parenthesis thin space left parenthesis straight c plus straight a right parenthesis                                                ...(2)
or space space open vertical bar table row cell negative 2 straight a end cell cell space space space straight a plus straight b end cell cell space space space space space straight a plus straight c end cell row cell straight b plus straight a end cell cell space space space minus 2 straight b end cell cell space space space space straight b plus straight c end cell row cell straight c plus straight a end cell cell space space straight c plus straight b end cell cell space space space minus 2 straight c end cell end table close vertical bar space equals space straight k left parenthesis straight a plus straight b right parenthesis thin space left parenthesis straight b plus straight c right parenthesis thin space left parenthesis straight c plus straight a right parenthesis
Put space straight a space equals space 0 comma space space space straight b space equals space 1 comma space space straight c space equals space 1
therefore space space space space open vertical bar table row 0 cell space space space 1 end cell cell space space space 1 end cell row 1 cell space space minus 2 end cell cell space space space space space 2 end cell row 1 cell space space 2 end cell cell space space minus 2 end cell end table close vertical bar space equals space straight k left parenthesis 0 plus 1 right parenthesis thin space left parenthesis 1 plus 1 right parenthesis thin space left parenthesis 1 plus 0 right parenthesis
therefore space space space space open vertical bar table row 0 cell space space space space space space space 0 end cell cell space space space space space space 1 end cell row 1 cell space space space minus 4 end cell cell space space space space space space 2 end cell row 1 cell space space space space space space 4 end cell cell space space space minus 2 end cell end table close vertical bar space equals space 2 space straight k space space space space space space space rightwards double arrow space space space space space space open vertical bar table row 1 cell space space space space minus 4 end cell row 1 cell space space space space space space space 4 end cell end table close vertical bar space equals space 2 space straight k
rightwards double arrow space space space 4 plus 4 space equals space 2 space straight k space space space space space space space space rightwards double arrow space space space space space space space 8 space equals space 2 space straight k space space space space space space space rightwards double arrow space space space straight k space equals space 4
therefore space space space from space left parenthesis 2 right parenthesis comma space space space increment space equals space 4 left parenthesis straight a plus straight b right parenthesis thin space left parenthesis straight b plus straight c right parenthesis thin space left parenthesis straight c plus straight a right parenthesis
or space space space space space space open vertical bar table row cell negative 2 straight a end cell cell space space space straight a plus straight b end cell cell space space space space straight a plus straight c end cell row cell straight b plus straight a end cell cell space space minus 2 straight b end cell cell space space space straight b plus straight c end cell row cell straight c plus straight a end cell cell space space straight c plus straight b end cell cell space space minus 2 straight c end cell end table close vertical bar space equals space 4 left parenthesis straight a plus straight b right parenthesis thin space left parenthesis straight b plus straight c right parenthesis thin space left parenthesis straight c plus straight a right parenthesis.
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 Multiple Choice QuestionsMultiple Choice Questions

130.

Let A be a square matrix of order 3 × 3, then | kA | is equal to 


  • k | A |
  • k2 | A |
  • 3| A |
  • 3| A |
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