What makes the fundamental theorem of calculus so fundamental ?
Why is there a variable -LRB- usually x -RRB- in the Second Fundamental Theorem of Calculus ? Would n't it be just as true if the theorem were defined as true for any interval ` a ' to ` b ' , instead of ` a ' to ` x ' ? What does the x signify , is it possible that the SFT could be defined another way ?