What is a wave function?
There are many interpretations of the wave function. Let's consider the simplest. The wave function is an abstract vector in a Hilbert space. It is assigned to particles and represents all the possible outcomes of measurements performed on the particle. Each dimension of the Hilbert space represents each possible outcome of a measurement. For example, an electron in a box will have a Hilbert space of many location possibilities within (and outside) the box. The moment a position measurement is performed (say, by opening the box and seeing where the electron ACTUALLY is), the electron stops being in an abstract state of 'could be anywhere' to being in a definite location in space. This is called the collapse of the wave function, when the act of measurement randomly selects one possibility to become reality. In general, a wave function represents all the possibilities waiting to become reality.
What foods should I eat if I want to lose weight?
In order to lose weight it is necessary to be in a state of caloric restriction. There are 3 types of nutrients that contain calories, or energy: protein, carbohydrates, and fats. The healthiest options, especially for weight loss, would be as follows: Protein: chicken, steak, fish, milk, eggs. Carbohydrates: oats, sweet potatoes, brown rice, kale, broccoli, whole wheat bread, whole wheat pasta, and basically any fruit. Fats: avocados, peanuts, almonds, olive oil, fish oil, peanut butter, almond butter. The key is to consume a moderate amount of this food such that you end up in a caloric deficit at the end of the day. Nothing beats tracking calories, but just listen to your body, monitor your weight, and adjust accordingly.
What is the derivative f'(x) of a function f(x)?
f'(x) represents how much f(x) is changing with respect to x. Formally, f'(x) is the slope of the tangent line at every point along f(x).