F'(X); NO DY/DX IS SUPERIOR; F'(X) LET'S YOU REAP ALL THE BENEFITS OF FUNCTION NOTATION, LIKE COMPOSITION. DY/DX IS OFTEN MORE INTUITIVE AND EASY TO REMEMBER, BECAUSE IT LOOKS LIKE A FRACTION, AND YOU CAN ABUSE ITS NOTATION LIKE IN A U SUB OR SEPARABLE DIFF EQ. FURTHER IT'S BETTER FOR IMPLCIT DIFFERENTIATION. NO F'(X) IS SUPERIOR, BECAUSE FOR HIGHER ORDER DERIVATIVES YOU ONLY HAVE TO ADD A DASH, OR NUMBER ONCE, WHERE AS FOR DY/DX YOU HAVE TO DO IT TWICE