Suppose MU1 (2,3) = 7 ; I'm having a really hard time unsrestanding this for some reason, how would one more of good one make seven? Is it that one unit of good one is worth 2 utils and one unit of good two is worth 3 utils so that if you added one more unit of good one it would be 2+2+3=7? I keep seeing it explained as "if you are consuming 2 units of good one and 3 units of good two, then 1 additional unit of good one will increase my utility by 7 utils" but wouldent that be 5? I just can't quite grasp what the reasoning and math is behind this answer, do I need to take a derivitive of something?