A function \( f ( x ) \) and interval \( [ a , b ] \) are given. Check if the Mean Value Theorem can be applied to \( f \) on \( [ a , b ] \) . If so, find all values \( c \) in \( [ a , b ] \) guaranteed by the Mean Value Theorem Note, if the Mean Value Theorem does not apply, enter DNE for the \( c \) value.
\( f ( x ) = 6 \ln x - 2 \) on \( [ 1,7 ]\)
\(c = \square \quad \) (Separate multiple answers by commas.)