.htaccess redirect to www with wordpress in a /blog folder?

Wordpress is set up at www.domain.com/blog/ on one of my domains. I thought it would be easy to get domain.com/blog/ to properly forward all requests to the www version, but I'm having some problems. Can anyone help? This is what I have been trying.

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTP_HOST} ^domain\.com$ [NC]
RewriteRule ^(.*)$ http://www.domain.com/$1 [R=301,L]
</IfModule>
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /blog/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]
</IfModule>

# END WordPress

Code (markup):

 

Try

<IfModule mod_rewrite.c>
Options -Indexes
Options +FollowSymlinks
RewriteEngine on
RewriteBase /
RewriteRule ^(.*)$ http://www.urdomain.com/$1 [R=301,L]
</IfModule>
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /blog/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]
</IfModule>

# END WordPress

Code (markup):

 

That didn't work unfortunately. I got a 500 error code.

 

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /blog/

RewriteCond %{HTTP_HOST} ^domain\.com$ [NC]
RewriteRule ^(.*)$ http://www.domain.com/$1 [R=301,L]


#is what is below generated by wp? If yes then leave it otherwise remove it.
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]
</IfModule>

# END WordPress

Code (markup):

 

Thank you!!