ALGEBRA(Sum of Absolute Value Differences)
posted by please help me out!! .
As x ranges over all real values, what is the minimum value of f(x)=x−123+x−456+x−789?

Note that xa+xb is constant (ba) for a<=x<=b
So, since x123+x789 is constant for 123<=x<=789, the minimum occurs at x=456, and is 666.