The function ( f ) is defined as ( f(x)=5/2x²-6 ). Find ( f(x-4) ). Write your answer without parentheses, and simplify it as much as possible. ( f(x-4)= )
a) ( 5/2x²-38 )
b) ( 5/2x²-22 )
c) ( 5/2x²-10 )
d) ( 5/2x²-14 )