The Derivative Song Lyrics - Tom Lehrer

To "there'll be some changes made". 

You take a function of x and you call it y, 

Take any x-nought that you care to try, 

You make a little change and call it delta x, 

The corresponding change in y is what you find nex', 

And then you take the quotient and now carefully 

Send delta x to zero, and I think you'll see 

That what the limit gives us, if our work all checks, 

Is what we call dy/dx, 

It's just dy/dx.