Set Memory Limit in htaccess [closed]

Question

I am working on WordPress. I need to increase the memory, so I added the following line to my .htaccess file

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

php_value memory_limit 64M

my sample php page

<?php
phpinfo(); 

but it throws the 500 internal server error. what is the problem here..