નાં વિસ્તરણમાં T6 = 84 તો x = ......... .   from Mathematics દ્વિપદી પ્રમેય

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Gujarati JEE Mathematics : દ્વિપદી પ્રમેય

Multiple Choice Questions

71.
(1 - 3x2 + 10x5)n અને (1 + x7)n ના વિસ્તરણમાં સહગુણકોનો સરવાળો અનુક્રમે p અને q હોત, તો............(n>1)
  • p = q3
  • pq = 42n
  • p + q = pq
  • p : q = 4

72. (1 + t2)12 (1 + t12) (1 + t24) માં t24 નો સહગુણક ....... છે.
  • open parentheses table row bold 12 row bold 6 end table close parentheses bold space bold plus bold space bold 1
  • open parentheses table row bold 12 row bold 6 end table close parentheses bold space bold plus bold space bold 3
  • open parentheses table row bold 12 row bold 6 end table close parentheses bold space bold plus bold space bold 3
  • open parentheses table row bold 12 row bold 6 end table close parentheses bold space bold plus bold space bold 2

73. (a+b+c)12 ના વિસ્તરણમાં a3 b4 c5 નો સહગુણક ...... છે.
  • fraction numerator bold left parenthesis bold 12 bold right parenthesis bold space bold factorial over denominator bold 3 bold space bold factorial bold space bold 4 bold space bold factorial bold space bold 5 bold space bold factorial end fraction
  • open parentheses table row bold 12 row bold 5 end table close parentheses bold space bold cross times bold space open parentheses table row bold 7 row bold 3 end table close parentheses
  • open parentheses table row bold 12 row bold 3 end table close parentheses bold space open parentheses table row bold 12 row bold 4 end table close parentheses bold space open parentheses table row bold 12 row bold 5 end table close parentheses
  • open parentheses table row bold 12 row bold 4 end table close parentheses bold space bold cross times bold space open parentheses table row bold 8 row bold 3 end table close parentheses

74. (1 + x2)4 (1 + x3)7 (1 + x4)12 ના વિસ્તરણમાં x11 નો સહગુણક ...... છે.
  • 1120
  • 1106
  • 1113
  • 1051

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75. (x + 5)6 ના વિસ્તરણમાં T1 = 729 તો ......... .
  • T3 = 30375, x = ± 3
  • T4 = ± 67500, x = ±3
  • x = 3, T2 = -7290
  • T2 = 7290, x = -3

76. open parentheses bold x over bold 2 bold minus bold 3 over bold x to the power of bold 2 close parentheses to the power of bold 10 માં x4 નો સહગુણક ......... છે. 
  • bold 405 over bold 256
  • 504 over bold 256
  • bold 450 over bold 263
  • આપેલ પૈકી એક પણ નહી

77. (1 + x)2n+12 માં મોટામાં મોટો સહગુણક ......  છે.
  • fraction numerator bold 2 bold space bold factorial over denominator bold left parenthesis bold n bold plus bold 6 bold right parenthesis bold space bold factorial end fraction
  • open parentheses table row cell bold 2 bold n bold plus bold 12 end cell row cell bold n bold plus bold 6 end cell end table close parentheses
  • fraction numerator bold left parenthesis bold 2 bold n bold plus bold 12 bold right parenthesis bold factorial over denominator bold left square bracket bold left parenthesis bold n bold plus bold 6 bold right parenthesis bold factorial bold right square bracket to the power of bold 2 end fraction
  • open parentheses table row cell bold 2 bold n bold plus bold 12 end cell row cell bold n bold plus bold 7 end cell end table close parentheses

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78. open curly brackets bold left parenthesis bold 9 to the power of bold x bold minus bold 1 end exponent bold plus bold 7 bold right parenthesis to the power of begin inline style bold 1 over bold 2 end style end exponent bold plus bold space bold left parenthesis bold 3 to the power of bold x bold minus bold 1 end exponent bold plus bold 1 bold right parenthesis to the power of begin inline style fraction numerator bold minus bold 1 over denominator bold 5 end fraction end style end exponent close curly brackets to the power of bold 7નાં વિસ્તરણમાં T= 84 તો x = ......... .  
  • 3
  • 1
  • 2
  • 1 અથવા 2 

B.

1

C.

2

D.

1 અથવા 2 

Tips: -

bold T subscript bold 6 bold space bold equals bold space open parentheses table row bold 7 row bold 5 end table close parentheses bold space open parentheses bold 9 to the power of bold x bold minus bold 1 end exponent bold plus bold 7 close parentheses to the power of begin inline style bold 2 over bold 2 end style end exponent bold space open parentheses bold 3 to the power of bold x bold minus bold 1 end exponent bold plus bold 1 close parentheses to the power of begin inline style fraction numerator bold minus bold 5 over denominator bold 5 end fraction end style end exponent bold space bold equals bold space bold 84 bold space

bold therefore bold space bold 21 bold space bold left parenthesis bold 9 to the power of bold x bold minus bold 1 end exponent bold plus bold 7 bold right parenthesis bold space bold equals bold space bold 84 bold space bold left parenthesis bold 3 to the power of bold x bold minus bold 1 end exponent bold plus bold 1 bold right parenthesis

bold therefore bold space bold 3 to the power of bold 2 bold x end exponent over bold 9 bold space bold plus bold space bold 7 bold space bold equals bold space bold 4 bold space open parentheses bold 3 to the power of bold x over bold 3 bold plus bold 1 close parentheses

bold therefore bold space bold 3 to the power of bold 2 bold x end exponent bold space bold plus bold space bold 63 bold space bold equals bold space bold 12 bold space bold times bold space bold 3 to the power of bold x bold space bold plus bold space bold 36 bold space

bold therefore bold space bold left parenthesis bold 3 to the power of bold x bold right parenthesis to the power of bold 2 bold space bold minus bold space bold 12 bold space bold times bold space bold 3 to the power of bold x bold space bold plus bold space bold 27 bold space bold equals bold space bold 0 bold space

bold therefore bold space bold left parenthesis bold 3 to the power of bold x bold minus bold 3 bold right parenthesis bold space bold left parenthesis bold 3 to the power of bold x bold minus bold 9 bold right parenthesis bold space bold equals bold space bold 0
bold therefore bold space bold 3 to the power of bold x bold space bold equals bold space bold 3 અથવા bold 3 to the power of bold x bold space bold equals bold space bold 9

bold therefore bold space bold x bold space bold equals bold space bold 1 અથવા x = 2

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