If a2 + b2 + c2 = 16,  x2 + y2 + z2 = 25  and ax + by + cz = 2

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 Multiple Choice QuestionsMultiple Choice Questions

121.

If x2 + y2 + 2x + 1 = 0, then the value of x31 + y35 is

  • -1

  • 0

  • 1

  • 1

317 Views

122.

If open parentheses straight x minus 1 over straight x close parentheses squared space equals space 3 comma then the value of open parentheses straight x to the power of 6 space plus space 1 over straight x to the power of 6 close parentheses equals

  • 90

  • 100

  • 110

  • 110

499 Views

123.

If a3 = 117 + b3  and a = 3 + b, then the value of (a + b) is

  • plus-or-minus space 7
  • plus-or-minus space 49
  • plus-or-minus space 13
  • plus-or-minus space 13
420 Views

124.

If a + b + c = 0 then the value of fraction numerator 1 over denominator left parenthesis straight a plus straight b right parenthesis thin space left parenthesis straight b plus straight c right parenthesis end fraction space plus space fraction numerator 1 over denominator left parenthesis straight b plus straight c right parenthesis thin space left parenthesis straight c plus straight a right parenthesis end fraction space plus space fraction numerator 1 over denominator left parenthesis straight c plus straight a right parenthesis space left parenthesis straight a plus straight b right parenthesis end fraction is

  • 0

  • 1

  • 3

  • 3

230 Views

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125.

If a2 + b2 + c2 = 16,  x2 + y2 + z2 = 25  and ax + by + cz = 20, then the value of fraction numerator straight a plus straight b plus straight c over denominator straight x plus straight y plus straight z end fraction is

  • 3 over 5
  • 5 over 3
  • 4 over 5
  • 4 over 5


C.

4 over 5
left parenthesis ax plus by plus cz right parenthesis squared space equals space left parenthesis 20 right parenthesis squared space equals space 400 space space space... left parenthesis straight i right parenthesis
left parenthesis straight a squared plus straight b squared plus straight c squared right parenthesis thin space left parenthesis straight x squared plus straight y squared plus straight z squared right parenthesis space equals space 25 space cross times space 16 space equals space 400 space... left parenthesis ii right parenthesis
From (i) and (ii)
left parenthesis ax plus by plus cz right parenthesis squared space equals space left parenthesis straight a squared plus straight b squared plus straight c squared right parenthesis space left parenthesis straight x squared space plus space straight y squared space plus space straight z squared right parenthesis
straight a squared straight x squared space plus space straight b squared straight y squared space plus space straight c squared straight z squared space plus space 2 abxy space plus space 2 bcyz space plus space 2 acxz
equals space straight a squared straight x squared space plus space straight a squared straight y squared space plus space straight a squared straight z squared space plus space straight b squared straight x squared space plus space straight b squared straight y squared space plus space straight b squared straight z squared space plus space straight c squared straight x squared space plus space straight c squared straight y squared space plus straight c squared straight z squared
⟹  a2y2 + a2z2 + b2x2 + b2z2 + c2x2 + c2y2 = 2abx + 2bcyz + 2acxz
⟹  a2y2 - 2abxy + b2x2 + a2z2 + c2x2 - 2acxz + b2z2 + c2y2 - 2bcyz = 0
⟹  (ay - bx)2 + (az - cx)2 + (bz - cy)2 = 0
⟹   ay - bx = 0  ⟹  ay = bx  ⟹  straight a over straight b space equals space straight x over straight y
      az - cx = 0  rightwards double arrow space space space az space equals space cx space space rightwards double arrow space space straight a over straight c space equals space straight x over straight z
     therefore space space space straight a space equals space kx semicolon space space straight b space equals space ky semicolon space space straight c space equals space kz
therefore space space space straight a squared space plus space straight b squared space plus space straight c squared space equals space 16
rightwards double arrow space space space space space straight k squared left parenthesis straight x squared space plus space straight y squared space plus space straight z squared right parenthesis space equals space 16
rightwards double arrow space space space space space straight k squared space cross times space 25 space equals space 16
rightwards double arrow space space space space space straight k squared space equals space 16 over 25 space rightwards double arrow space space space straight k space equals space 4 over 5

   therefore space space space fraction numerator straight a plus straight b plus straight c over denominator straight x plus straight y plus straight z end fraction space equals space straight k space equals 4 over 5




 



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126.

The value of x which satisfies the equation fraction numerator straight x plus straight a squared plus 2 straight c squared over denominator straight b plus straight c end fraction plus fraction numerator straight x plus straight b squared space plus 2 straight a squared over denominator straight c plus straight a end fraction plus fraction numerator straight x plus straight c squared plus 2 straight b squared over denominator straight a plus straight b end fraction space equals space 0
is

  • (a2 + b2 + c2)

  • - (a2 + b2 + c2)

  • (a2 + 2b2 + c2)

  • (a2 + 2b2 + c2)

394 Views

127.

If straight x space equals space fraction numerator square root of 5 plus 1 over denominator square root of 5 minus 1 end fraction space and space straight y space equals space fraction numerator square root of 5 minus 1 over denominator square root of 5 plus 1 end fraction comma the value of fraction numerator straight x squared plus xy plus straight y squared over denominator straight x squared minus xy plus straight y squared end fraction is

  • 3 over 4
  • 4 over 3
  • 3 over 5
  • 3 over 5
389 Views

128.

Let 0 < x < 1. Then the correct inequality is

  • straight x space less than space square root of straight x space less than space space straight x squared
  • square root of straight x space less than space straight x space less than space straight x squared
  • straight x squared space less than space straight x space less than space square root of straight x
  • straight x squared space less than space straight x space less than space square root of straight x
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129.

If x4 + 2x3 + ax2 + bx + 9 is a perfect square, where a and b are positive real numbers, then the values of a and b are

  • a = 5,  b = 6

  • a = 6,  b = 7

  • a = 7,  b = 6

  • a = 7,  b = 6

1312 Views

130.

If (a + b)2 = 100 and (a - b) = 4, then ab equals to

  • 116

  • 84

  • 21

  • 21

50 Views

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