During the 60s and 70s, name a book or publication that was part of the new wave of environmentalism, what it discussed, and how it influenced the movement.

The main publication that comes to mind is Rachel Carson's Silent Spring. This book brought to light issues that were affecting all organisms globally. Silent Spring talked about biomagnification of dioxin, and what the effects of of it could be in humans. This led to widespread awareness and eventual restrictions put in place by law.

What is a limit and how does it relate to a derivative?

A limit is an operation performed on some kind of curve. You specify parameters for the dependent variable, and the result is a independent variable value. The limit operation is used to define the derivative of a function, also known as the instantaneous rate of change. In other words, taking the limit is the operation used to define what a derivative is.

What is the difference between pass-by-value and pass-by-reference?

Pass-by-value makes a copy of the argument passed in. Pass-by-reference makes a copy of the address of the argument. Pass-by-reference should always be used when passing a user-defined object that is an instance of a struct or class, because, otherwise, you will generating unnecessary copies of that object. Pass-by-value should be used for variables that non-user-defined, such as int's and char's.