Thank you very much! I understand (for the most part)

Although I got stuck on this one...

Below, find lim f(x+h) - f(x) / h
----------- (x->0)



I tried it and got the first step as:

(4/x+h) - (4/x) / h

At this step, I'm pretty sure I'm on the wrong track but I multiplied both top & bottom by (4/x + h) + (4/x)

Again, it turns out weird and I'm lost...