Evaluate:

http://img254.imageshack.us/img254/1089/66008797.png

where a and b are positive real numbers. (Here max(s,t) is defined as the larger of the two numbers s and t.)

how do i even begin this? I am not familiar with this max(s,t) function, how does one determine which is greater in this case (depends on x and y, right?).