Principle Of Mathematical Induction

Question
CBSEENMA11014499

The 4th term in the expansion of open parentheses ax plus 1 over straight x close parentheses to the power of straight n is <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)
#1 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php(56): mkdir('/home/config_ad...', 493)
#2 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/FolderTreeStorageAndCache.class.php(110): com_wiris_util_sys_Store->mkdirs()
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#4 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/TextServiceImpl.class.php(59): com_wiris_plugin_impl_RenderImpl->computeDigest(NULL, Array)
#5 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/service.php(19): com_wiris_plugin_impl_TextServiceImpl->service('mathml2accessib...', Array)
#6 {main}</pre> Find the values of a and n.

Solution

4 to the power of th term in the expansion of open parentheses ax plus 1 over straight x close parentheses to the power of straight n = 5 over 2

rightwards double arrow                      <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)
#1 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/util/sys/Store.class.php(56): mkdir('/home/config_ad...', 493)
#2 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/FolderTreeStorageAndCache.class.php(110): com_wiris_util_sys_Store->mkdirs()
#3 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/RenderImpl.class.php(231): com_wiris_plugin_impl_FolderTreeStorageAndCache->codeDigest('mml=<math xmlns...')
#4 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/lib/com/wiris/plugin/impl/TextServiceImpl.class.php(59): com_wiris_plugin_impl_RenderImpl->computeDigest(NULL, Array)
#5 /home/config_admin/public/felixventures.in/public/application/css/plugins/tiny_mce_wiris/integration/service.php(19): com_wiris_plugin_impl_TextServiceImpl->service('mathml2accessib...', Array)
#6 {main}</pre>                        rightwards double arrow      space space straight C presuperscript straight n subscript 3 space left parenthesis ax right parenthesis to the power of straight n minus 3 end exponent. space open parentheses 1 over straight x close parentheses cubed space equals space 5 over 2
 
  rightwards double arrow    straight C presuperscript straight n subscript 3 space straight a to the power of straight n minus 3 end exponent. space straight x to the power of straight n minus 3 end exponent space cross times 1 over straight x cubed equals 5 over 2             rightwards double arrow             straight C presuperscript straight n subscript 3 space straight a to the power of straight n minus 3 end exponent. space straight x to the power of straight n minus 6 end exponent space equals space 5 over 2           ...(i)
The R.H.S. is independent of x
rightwards double arrow              straight x to the power of straight n minus 6 end exponent space equals space straight x to the power of 0
or                      n - 6 = 0
∴                         n = 6
Also, from (i),
 
                   straight C presuperscript 6 subscript 3 space straight a to the power of 6 minus 3 end exponent. space straight x to the power of 0 space equals space 5 over 2
rightwards double arrow                  fraction numerator 6 factorial over denominator 3 factorial space 3 factorial end fraction straight a cubed space equals space 5 over 2           rightwards double arrow                20 space straight a cubed space equals space 5 over 2
rightwards double arrow                   straight a cubed space equals space fraction numerator 5 over denominator 2 cross times 20 end fraction equals 1 over 8 equals open parentheses 1 half close parentheses cubed
∴                    straight a equals 1 half
Hence, n = 6 and straight a equals 1 half.