Find a, if the co-efficients of x2 and x3 in the expansion of

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 Multiple Choice QuestionsShort Answer Type

71.

Find the 4th term from the end in the expansion of <pre>uncaught exception: <b>mkdir(): Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php at line #56mkdir(): Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php line 56<br />#0 [internal function]: _hx_error_handler(2, 'mkdir(): Permis...', '/home/config_ad...', 56, Array)
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#6 {main}</pre>

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72.

Find the 11th term from the end in the expansion of open parentheses 2 straight x minus 1 over straight x squared close parentheses to the power of 25

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73. Prove that in the expansion of (a + b)n, the co-efficients of terms equidistant from the beginning and end are the same.
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 Multiple Choice QuestionsLong Answer Type

74.

Find n, if the ratio of the fifth term from the beginning to the fifth term from the end in the expansion of open parentheses fourth root of 2 plus fraction numerator 1 over denominator fourth root of 3 end fraction close parentheses to the power of straight n is square root of 6 colon 1.

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 Multiple Choice QuestionsShort Answer Type

75. Find the co-efficient of straight x to the power of 5 space in space left parenthesis straight x plus 3 right parenthesis to the power of 8
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76. Find the co-efficient of:
straight a to the power of 5 straight b to the power of 7 space in space left parenthesis straight a minus 2 straight b right parenthesis to the power of 12.
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77. Find the positive value of m for which the co-efficient of x2 in the expansion of (1 + x)m is 6.
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78. In the expansion of (1 + x)n, the co-efficients of xp-1 and of xq-1 are equal. Show that p + q = n + 2, p ≠ q.
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79. In the expansion of (1 + a)m+n , prove that co-efficient of am and an are equal.
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80. Find a, if the co-efficients of x2 and x3 in the expansion of (3 + ax)9 are equal. 


Term containing straight x squared comma in the expansion of left parenthesis 3 plus ax right parenthesis to the power of 9 space equals space straight C presuperscript 9 subscript 2 space 3 to the power of 7 space left parenthesis ax right parenthesis squared
Co-efficient of straight x squared space equals space straight C presuperscript 9 subscript 2 times space 3 to the power of 7 space straight a squared
Term containing <pre>uncaught exception: <b>mkdir(): Permission denied (errno: 2) in /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php at line #56mkdir(): Permission denied</b><br /><br />in file: /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php line 56<br />#0 [internal function]: _hx_error_handler(2, 'mkdir(): Permis...', '/home/config_ad...', 56, Array)
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#6 {main}</pre> in the expansion of left parenthesis 3 plus ax right parenthesis to the power of 9 space equals space straight C presuperscript 9 subscript 3 space 3 to the power of 6 space left parenthesis ax right parenthesis cubed
  Co-efficient of straight x cubed space equals space straight C presuperscript 9 subscript 3. space 3 to the power of 6. space straight a cubed

From the condition of the question, 

                      straight C presuperscript 9 subscript 2 times 3 to the power of 7 times straight a squared space equals space straight C presuperscript 9 subscript 3 times space 3 to the power of 6 times space straight a cubed

rightwards double arrow              36 times 3 to the power of 7 times straight a squared space equals space straight C presuperscript 9 subscript 3 times 3 to the power of 6 times straight a cubed

rightwards double arrow                  108 straight a squared equals 84 straight a cubed

rightwards double arrow                   108 = 84a

rightwards double arrow                                straight a equals 108 over 84 equals 18 over 14 equals 9 over 7

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